On the one hand I've never been real convinced rear disk made a big difference, but on the other I think I'd convert to disk before swapping to a smaller drum setup.
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...