'64 Dart GT: 273 to 325 swap ?

I understand that the 273 was made as a lightweight V8 for the compact Darts in '64. It was made from some 318 poly parts, and if I remember right, the '64 4-speed trans would also accept the 318 poly. Knowing this, I was wondering if the '57 325 block would also mate to it. I said "poly/hemi" above because the 315 & 325 blocks and intakes could be used with either the poly or hemi heads. It's a shame, but the car sat in the weeds for a few years, and the frame rails got soft. Rather than having them completely replaced, I thought I'd box them and go the nostalgia route, with leafs and a straight axle. The car is too far gone for a concourse restoration. So, I've decided to rod it a little. And, yes, I'd be after the cool factor with a small early hemi. Of course, upgrades would be done to the braking system as well. I'm just wondering how / if the 325 would fit, mate to the 4-speed (spline issues ?), etc. Alright then, if I do decide to go with a built small block LA instead, what are those suggestions ? Thanks for your help all ! :prayer: