Hmm, that’s a ‘96+ Vortec motor, 350 I’m assuming. I’m not gonna lie, it looks a bit rough in terms of the quality of work done and care it received. As far as the keys go, you’ll need to replace all the cylinders. Ignition is probably gonna be the least headache and most important for the purpose of getting it started. Then you’ve got the two doors and the rear window/tailgate. So no door key? That master cylinder looks pretty worrisome, and the way the electronic components are tossed around worries me about the condition of parts that aren’t visible. Hackery is what I’m getting at. You need a clutch, a fan, and the upper portion of the shroud, too. I’d clean all that junk out of there, and it should look a little less daunting. Once you’ve cleaned it up, replaced the ignition cylinder, at least put a cooling fan on and relocated the obstructions for the fan and shroud, I’d get to work on trying to start it. You’ll need a battery, of course, an oil and filter change, and fresh fuel at the minimum. You can worry about ignition and fuel system tuneups immediately after getting it started. If you can clean up the wiring and mounting of that stuff on the driver’s side, I’d just run the Vortec setup and ABS if the engine’s in decent shape. If it’s full of problems and gremlins that aren’t mechanical in nature, I’d re-TBI it (with the appropriate tuning for a better than TBI engine setup) or put a Quadrajet on there and be done with it. The heads are pretty well sought after so if the engine’s good, you’re already ahead. Do you have any background info on it? Maybe
@gmachinz can give you some pointers on the wiring situation.