Lost in Restoration
Looks like you found a decent one.
I think the 340 Exhaust manifolds are a good idea. Thats what I have on my 318 Dart.
Swapping rear ends should really be no big deal. But you may have to find a shorter driveshaft because the 8-3/4 centerchunk is longer (front to back) than the 7-1/4" rear.
Good luck