wiring up my hei '74 401 cherokee

Ditto. OEM ammeters only measure what goes in & out of the battery (cranking excluded!!) and not what the alternator puts out, etc. Hence they normally read zero Amps - exclusions being after cranking (replacing lost charge), step changes (till the alternator steps up or down), or alternator shortfalls (idling; excessive loads). If you connect loads to the battery (like audio, PCs etc), the Amperage means nothing tho battery ground (shunt) ammeters may give valid readings. An ammeter will not tell you if you are overcharging, undercharging, the battery condition, nor if the alternator isn't quite sufficient. And tho OEM voltmeters are (usually) wired across ignition, that is usually not an accurate battery voltage (which is what alternator voltage is all about) due to battery to ignition voltage differences which can be 1V or more - and the difference between a 14.4V and 14.5V or 14.6V battery charge voltage can have a significant effect on battery health. Hence why I say to add one across the battery, else rewire the OEM, and add an IGN controlled relay to disable the voltmeter when IGN is off. Of course for analog (electro-mechanical) voltmeters, such errors are probably undetectable. A 3-digit voltmeter is ideal - eg, 12.9V, 26.7V, etc. (4 digit is way to accurate and bobbly for normal use.)   

When using an analog voltmeter of unknown accuracy, compare its readings to a known to be accurate meter. Do this at various operating conditions of the vehicle. Its easier to detect a change in pointer position than a static pointer position. I.E. Does the pointer deflect as various loads are turned on? This is helpful in determining if various systems are operational.

Okay that is a lot to take in all at once I will try to draw up what has been suggested, as that is how I may understand this better. Then it should make sense to me. For the record and in case it has been missed, I no longer have the ammeter. They became a fire hazard in these old Jeeps as the wires get older and what not. I have replaced it with a volt meter. Thank you very much for taking your time and helping me with this.

In return, thanks! for your fire hazard comment. That's why automotive modern ammeters are shunts - ie, a calibrated voltmeter that measures the voltage drop across an in-line resistor (I=V/R) - so that the heavy current (path) is not routed thru the cabin - only a couple of mA rated wires for the voltmeter. But as I said, ammeters are usually only for experimentations etc, and I am still to find out their success in certain modern vehicles. My 1960s vehicle had the same as yours - battery+ terminal in to the gauge and back out to the car +12V feed (alternator output etc) - NO fuse. The only thing worse is competitive vehicles that have +12V cabin and maybe rear corner mounted battery isolation switches... they are sized to carry cranking currents rather than the usual 30A or 60A max of cabin ammeters. (I laugh when I see such implementations flame!) (Reconsidering - one thing worse is combined engine kill & isolation switches! I look forward to lawsuits.)    Anyhow, lots of extra information. But your basic OP answer is (IMO) simple - namely use the original IGN +12V igCoil feed to power your HEI and igCoil, else use it to energise a relay to power them - eg, via 20A-30A fuse with (say) 30A cable direct from batt+. Ask if you need more info on interpreting a/the voltmeter, or anything else.

That is what I forgot to mention, The HEI I will be using is an internal coil ( Think G.M.) not the external that the factory was.

I'm not familiar with it. I am familiar with some of the Delco/Delphi systems but they are typical reluctor & ignitor with external igCoil(s) (tho their ignitors are ECU interactive (viz HEI-8 or whatever they were), and their reluctor generation seemed to lag a few years). Try first using the original IGN +12V wire to the ballast end of the igCoil. If that wire gets warm or hot (compared to its surroundings), use the relay.

Integral coil HEI distributors typically use a minimum of 14 gauge wire for their power wire.

Sorry lads but you brought back memories from around the 1970s of rewiring battery to gauge looms on London Taxis and Ford Capris. You know what they had in common don't you. The taxis were a joy, 100,000 a year and covered in caked on diesel etc. etc.

Okay this is what I came up with, with what I understand. Basic drawing of what I have. The "S" terminal on the starter solenoid has a 16 gauge wire going through the bulkhead connector through the safety switch into the ignition switch. Out of the ignition switch is a 14 gauge wire that splits into the fuse box and goes through the bulkhead connector where it becomes a 20 gauge resistance wire, then becomes a 14 gauge wire again then connects to the coil (+). The "I" terminal is a 14 gauge wire that goes directly to the coil (+). Both wires connected to the coil (+). (Side note, do you like the wrapped around blue wire on the coil that goes through the firewall for the A/C? Previous owner or whoever did this. This is why I ask questions. I really hate wiring hacks.) At first I thought I could do this: But looking at it more and searching around, The "I" terminal only sends 12 volts momentarily. So I did this: This way it has full voltage going to the relay but only activated when I turn the key. Would I want to put a fusible link or circuit breaker "I" terminal and #30 on the relay? From the relay to the distributor is a 12 gauge wire. Or am I still not getting it?

The last fig looks ok. So instead of powering the igCoil, you energise the relay (86). Good idea! That overcomes the resistive wire which I assume is in lieu of a ballast resistor to drop voltage to an 8V "external resistor" type igCoil. The relay connects battery +12V #30 to #87 thus powering the HEI and its igCoil. Although you could put a fuse near the starter solenoid to #30, but the original did not have it and most igCoils don't have fuses for reliability and safety reasons - you really do not want to spark due to an aging fuse or extra connections. IMO it's better to rely on physical protection - make sure the connections and wiring is secure and well insulated. I assume the HEI needs no ballast resistor... It either has its own else like most modern ignitors, has current limiting so that any igCoil can be used.    I reckon that should work well. The only tip I'd give is to keep your original dizzy & igCoil (with ballast) with you in case - or when - the HEI or igCoil fails. If there is no ballast because that's done by the resistive wiring, then connect the relay's #86 to the igCoil when needed. With a ballast, connect the relay output 87 thru the ballast to igCoil+ (with igCoil- going to the points, and tacho if fitted). Good luck! PS - BTW, I suspect the solenoid's "I" is only momentarily +12V during cranking - ie, it's the ballast/resistive-wire bypass to give full +12V to the igCoil during cranking (which is not needed for HEI etc). And yes, I like the wire-wrapped +12V connection. Of course experienced quality practitioners like us would NEVER do anything like that... But the ones on my vehicle are still working fine.    (And they'll probably continue to work unless I decide to join them properly. But if it works, leave it alone - I'm certain that saying was invented from the times I finally cleaned up rats nests (or built proper PC boards for components) only to find total failure of the circuits involved. )