I like the way you're thinking. My cousin and I pulled a 263 out of a 53 several years ago. I kept thinking of how much it looked like a Stovebolt. It would definitely be something different.
From my research, they aren't great when it comes to performance, but the cool factor is definitely there.
If I remember right, the 263 was barely longer than a 235, and the 320 is a couple inches longer yet.
As far as getting it between the firewall and radiator, I can't say what would need to be done. Where there is a will there is a way.
