What's the donor vehicle - B or C body? And before I even touched that job I'd make sure the donor stuff is good before turning a single wrench, meaning it drives, shifts, doesn't overheat, etc; otherwise the finger pointing can ensue and you may be asked to fix a lot of stuff that wasn't part of the swap. Even to do a compression test, tune up and trans filter/band adjustment while it's still in the wagon, fresh carb rebuild if needed, etc. CYA...shake out any problems before pulling it from the wagon, while it's in the wagon. And double check the exhaust manifolds if you're reusing C body - because B and C body are going to be different. I seem to recall C body exiting on the driver side at a different angle than a B body.