1980 Chevy K10, Code Alarm CA5054

I have what may be a challenging install tomorrow and just wanted to see if anyone had any thoughts on this. First, it's had the engine and ECM swapped, I'm not trying to install RS on a carbureted truck. The main problem is there's no wiring diagrams available for this that I can find.
It may turn out to be real easy, all I should have to do is identify the starter,acc, ignition and 12v at the ignition switch, find a brake light and parking light wire. The customer says he'll show me the tach wire. No power locks of course, but I'm to leave the lock/unlock wires accessible for a later addition.
Anyway, just wondering if someone might know of any obstacles or funky wiring I should be prepared for, or has any tips on this. Thanks.

Well I guess I'll update, easy easy easy. The trim was a little tricky, and delicate, so I chose to use no battery powered tools for reassembly. I'd post some wire colors and locations, but very little was original from what I could tell.
One thing was kinda tricky, I had what I thought was an ignition wire, but had some doubts as it dropped to 3.4v during crank. I retested every wire with a clamp meter before soldering and discovered it was actually my most important accessory wire, when the draw jumped turning on the heater.