Poly question?!?!
I had a 65 Coronet 440 convert with the original 318 Poly and dual cable 727) in it. When the original transmission gave out, I used an early 70's 727LA, converted the steering column to a 66-up linkage and drove the heck out of it. As far as I know the 62 or 63 and up polys didn't have the extended crank flange making a late 727/904 change much easier. There is a 318 poly group over at Yahoo for more info.