What is different as far as the bell housing and gimble ring on these 2 transom assemblies? I know that the inner transom plate, steering tiller arm, upper pivot shaft, the outer gimble ring housing, and several other small items are the same, so figure the gimble ring has to be somewhat close.
Trying to determine what all parts I would need to locate if I were to go from a Alpha Gen 2 to a Bravo drive, other than the obvious.

i once thought the same thing,and in fact had been told by a pretty good wrench it'd work >NOT.Bite the bullet and buy a bravo transom assembly

the entire bravo assy. is heavier in design, and by the time you got done trying to piece it together, you could have bought a bravo assy and been done, alpha's are designed for 300 or so HP or less, Bravo's are rated to around 800 or so.
Merry Christmas
Larry