Hello, I recently purchased a 2000 GMC Sierra SLE 4-door 4x4 454 7.4L dually. Problem is it has an early 1990s 454 in it. The current head (90s series) has an exhaust crossover port but the intake manifold does not (its a 2000). This is causing issues with burning holes through the head gasket. This motor is clean and strong. It appears to be a remanned motor. I would like to know if it would be possible to put 2000 heads on this 1990 motor and have it run properly, or would it be possible to block these exhaust ports (on the 90 block). I have the 1990s heads and the truck ran with no codes when I bought it, but there were a lot of sensors not connected, the oil pressure and temperature gauge didn't work, the oil pan had been cut in half then welded together and there was oil leaking onto the manifold. When we opened it up to replace the gaskets we discovered the problem with the head gaskets. I would prefer to not replace the motor with a new one if possible.