if you only have the engine harness the swap can be done using caspers dash harness mate and youll be able to avoid having to research every wire in the lc2 harness
84/87 Dash Harness MateOur mating harness is designed to plug directly into the stock GM engine harness found on the Grand National and T-Type cars. This harness plugs into the bulkhead and provides fuses and necessary wiring to run the engine functions. It is used mainly for transplants. Comes comp
www.casperselectronics.com
be aware the dash harness mate doesn't support the starting/ charging systems
I helped to do a swap into a 34 ford LC2 engine and brf trans and used all the GN harnesses
did a c10 and used just the engine harness and cut the c100 end off going to the fuseblock and hotwired wired relays to power the various circuits only needing a 12v switched wire from the c10
easiest way to do the swap if you want lockup torque converter is get a dash harness (about same price as caspers dash mate harness, the harness will support the ignition module, injectors and relays for fan , it will also support the torque converter lockup control at brake pedal as well as the aldl and allow a gm style ignition switch based steering column
in addition to the dash having the body harness to rear and tail lamp harness and a front end harness make all that lighting wiring easier
caspers can build a harness for a hybrid install and it may seem expensive but the lc2 original harnesses can cost just as much and are 35yrs old wiring and need some work