It's definitely a 429 Thunderjet engine if it is out of a 1968 T-Bird. This was the first of
the 385 family of engines. They were available with either a 2V or 4V carb. It is basically
a large car engine. In 1970, the 429 Cobra Jet and Super Cobra Jet engines were made.
They both had better heads than the Thunder Jet with larger valves and ports and on
both Cobra Jet 429s had an adjutable valve train that could adjusted for solid lifter cams.
All regular Cobra Jet 429s built after 11-1-69 went back to non-adjustable valve train.
Super Cobra Jets still had a fully adjustable valve train and as always had 4 bolt main
bearings on no.s 2,3, and 4 journals. Cobra Jet 429s are very hard to find today.