'64 Dart GT: 273 to 325 swap ?

I would also have to argue that there is such a thing as a Poly/Hemi engine if speaking in terms of what engine to use without having bought it yet.
Some of the engines were made as both Poly and Hemis. I have a '56 270 Poly myself. Swapping heads would make it a 270 Hemi..

And for the record, I would not put a heavy 50's engine in an A-body. It will be a lot of work, make the car handle bad without massive upgrades and will not perform like a hot smallblock