Thanks to everyone who responded (with experience).
Why is this not done more often?
Is it hard to find a 55-62 higher-speed R&P?
The original poster has/had a 1954 3.90 enclosed driveshaft R&P.
Obviously, a readily available 3.90 would be better than a 48-53 4.11.
And, this would be faster, easier, and maybe less expensive than a 3.55 R&P conversion (around $300, plus all installation parts/bearings, which might/would be needed either way).
