I can't speak to how hard the swap would be, I just don't know. But I'm running similar size tires, a 3.08 geared rear, an SM420 and a GMC 270.

This is in my '55 1st Suburban and as long as I don't put a trailer behind it I think it drives fine. I get 14 running around town and maybe 17 on the highway.

1955 1st GMC Suburban | 1954 GMC 250 trailer puller project | 1954 GMC 250 Hydra-Matic | 1954 Chevy 3100 . 1947 Chevy COE | and more...
It's true. I really don't do anything but browse the Internet looking for trouble...