Your shop is in over their head. Cut your losses now. Contact the shop and tell them to stop all work, and itemize a bill. Do some research on what shop can take over the project. Be sure to discuss the project in detail with the shop manager. You may have to go out of your area.

What every one else said is correct: a matching engine and transmission with complete harness should run, even if It's sitting on the ground.

I doubled the cost of my 73 charger, and it's unfinished despite having spent more than enough to complete it, because I had the wrong shop, and didn't know when to pull the plug.