[olddog]

Some things that jumped out at me.

Early 289 engine had a different bell housing with one less bolt than later years. I would have to pull a book, but you should know the answer to which bell housing this engine takes. The older smaller one limits clutch size, I think. Not sure if a blow proof is available for it.

The 351 cam will interchange, but it is a different firing order than the other SB. I don't see why they thought a 351 cam would make more power. Lift and durration is the key. Never heard it claimed that the 351 fireing order increase scavenging affects and makes more power.

You want to ask if the engine was ballanced with damper and flexplate attached. What offset ballance is this engine?