Sorry your having so much trouble. Keep your receipts and try to get the "new" guys to comment on your engine issues on the work order explaining what they had to do to fix your engine as a result of the poor job done by the nutball. This is suitable evidence to bring to court should you want to.
BTW, it can be a challenge to re-install your heads while engine is in the car. Some of the head bolts could be difficult to torque. Is the transmission ok now?
If you have to pull the engine out again consider having the engine builder put engine on a test stand for testing etc so they can prove it works before you put it back in.
I would recommend you get a very experienced reputable Pontiac engine builder to complete your engine. It's never too late to get the job done right. Who knows what else could be waiting to break. And if you should decide to start a Lawsuit you have a much better chance of winning if you get it fixed by an unimpeachable engine builder.
