Haven't gone into bullet casting but I'd go as heavy as possible. If this was my 71, i would work up accuracy loads with the scope on and then (as you said) switch to one of those repro Lyman side mounted peeps that would cover some of the side mount holes. Buffalo arms makes the reproduction Model 21 Lyman. It would look great and disguise the mounting holes somewhat.
Much handier gun without the scope but it would be nice to have sometimes. My own 71 is capable of 300 yard trajectory and accuracy but my open site use at that range is a bit shaky.

https://www.buffaloarms.com/lyman-21-type-receiver-sight-for-model-95-86s-blued-ptclongb


good article on cast bullets

http://www.hensleygibbs.com/casting/castinthe348winchester.htm

Last edited by North61; 05/09/19.