I have 2 416's and a 45/110 that are fun to shoot (no muzzle brake
my limit is about 50 rds at a time.
The ruger #1 will only take a #5 tapered barrel due to the tang so any
thing from a 378 up should impress your friends.
Anything larger than a 460 in a 8 to 9 lb rifle will be brutal without a brake.
There is a "MAN" in Australia named Clive Downie that shoots a 729 Jongmans
with a 21lb rifle . The 1046gr solid travels at 2265ft/sec for 11941 ft/lbs.
I would think that about .600 head dia would be max for the ruger so plan
well an talk to a good smith before you start a project like this.
J E CUSTOM