Fresh swap will not crank.
 

Hoping you guys may have some thoughts, sorry in advance for the long post. I'm in the final stages of putting an LT1 into an 86 FC base model. It was going just fine until I tried to turn it on. Turn the key and nothing. All the electrical stuff works, lights, heater blowers etc... but it didn't even crank. Went around and check to make sure power was getting places and everything was hot. I'm good with the mechanical stuff but I'll be honest the wires and whatnot are over my head. Some things important. The LT1, wires and everything came out of an wrecked 87 T11. Its body was shot but the whole drivetrain was fine, except after the accident it wouldn't crank. Just figured it was a short somewhere. I tried to plug everything back in the way it was on the wreck but there were some differences. And I wrecked it so I know it ran just fine before the crash.

Any pointers where I should start looking or doing? Is it possible that the ECU was shorted out in the crash?

Can you roll the car in gear? Does the motor roll over at all? Check your grounds, specially starter/block ground

Well good news. Out of frustration I just hotwired the starter motor. She fired right up, first time I have heard it running in over a year! Still not sure why I can turn it on with the key, but at least a lot of problems have been narrowed down