Scott I intend to use the finished truck to pull a trailer. My alternative choice if I were not to go Cadillac would be Big Block Chevy. I too am tired of SBC's, though today three of my drivers are 350's, and I have eight more I could use someday.
BBO is big block Olds I assume. Are you using a BOP TH400? Because of the change in mount design the crossmember you've removed is a little different than the one in my way.
What are you doing for exhaust manifolds? I don't have the motor close enough to its final location yet to be sure, but I suspect that is going to give me fits too.