I find the above situation - and descriptions - confusing....
Normally HEIs - just like the IgnCoil - are powered from the ignition switch - specifically the IGN terminal which is on whilst cranking.
Cars that use external resistor coils - ie, a resistor or "ballasts" to drop 12V to about 8V - did so primarily for better spark. (Lower impedance for better response, and an ~8V coil for good spark even during cranking - ie, due to voltage drops.)
The resistor was bypassed during cranking to apply full system voltage to the IgCoil for a good spark.
(FYI - Although I changed my 12V IgCoil for an 8V IgCoil with external ballast, I never bothered with the bypass switch/relay; but I could have manually bypassed if needed.)
Most electronic ignitions do not need a ballast, but there are exceptions (and a few laughs!).
Modern systems tend to have current limiting so the type of coil is virtually irrelevant. (EG - my retrofitted reluctor and ignitor from a 1980s vehicle uses a 1.2 Ohm IgCoil (primary) but due to its current limiting I can use 0.3 Ohm primaries without a problem - except for erratic tacho readings!.)
FYI -
I recommend at least an HEI or similar. I replaced my points after ~120kkms (75,000 miles) only because its block had worn down. Its contacts were still shiny. Thanks to the HEI (with its static dwell), the only time I gapped the points was when they no longer opened. I'd merely rotate the distributor as the timing retarded until the next re-gap - usually after 20,000 miles). Points substitution is trivial compared to taking the load off them!
FYI#2 - I was totally into CDI (Capacitive Discharge Ignition) and was about to build a simple, cheap, powerful multi-trigger/output CDI for sequential spark etc (only $2 per extra input/output) until I upgraded with that "stock" 1980s ignition system - its starts cold with a 5V battery! (Even my CDI may not have fired below 6 or 8V.)
Not that that has much to do with your wiring problem, but I'm wondering what was done & why, or why there isn't the normal IGN powered starter (switch) or ignition circuit.
But that sort of wiring should be simple.
I recommend however upgrading some vintage aspects - eg, alternator with internal regulator; modern fuselinks off or near the battery (eg - plastic types, not the old wire types); duplication of modern "Ignition" relays that not only take the load off the ignition switch but also provide polarity protection (ie, if the battery is connected R'se about, the relay(s) will not energise and hence any connected EMS, computer, audio, entertainment system etc will not blow).
Of course, it depends how original you want to keep it.
My everydayer is a 1965 ute. It has many retrofits, but it can be returned to original condition. (EG - I never cut original wiring; I'll make translator harnesses else bypass.)