Massive oil leaks.

I'm guessing the "installer" broke or forgot to tighten the oil sender, oil gauge line, maybe took the oil filter off to get it in the car then it was loose or missing the gasket. Something along those lines. Your saying on the engine dyno he only ran it for 10sec??? Why GTO the trouble of hooking it up?? Most engine shops charge $500 or more to brake in and tune your new mill on the dyno and is usually a half to full day ordeal.