I installed the inexpensive Weaver aluminum bases. I used QD rings with thumb levers - set bottom halves and snugged up - used 1" diameter lapping bar to verify that each ring half had full bearing on the scope - was very minor - do not recall a mis-alignment at all. Installed a 2 1/2 power Leupold, which just "barely" fit - to get that front ring behind the front lens, not around the lens. Seems fine - a 458 Win Mag bought from Gagnon's in 2013.
Further, I removed the rear barrel sight - drilled and tapped into rear face of rear base and installed a little Redfield "flip up" aperture sight. I am pretty sure those were #3-56 screws - pretty tiny taps, etc. for fat fingers, as I recall. So, idea is to have an aperture sight as backup for the scope - should it ever die, which I doubt will happen. I found my front sight ramp to be installed on a very shallow dovetail, then some sort of glue or epoxy - due to my own klutzy-ness in trying to take out the front sight element, the entire front ramp came off. The screw under the front sight element does not go into the barrel - it goes into a "top hat" kind of mount, that sits in a shallow dovetail on the barrel - ramp slides down over that top hat, plus some kind of glue - not solder. Took some commotion to reinstall - do not really trust it - I plan to get or make a banded front sight ramp for it - something that I will be more certain does not go flying off into the bush one day... Because of the cartridge, I also need to figure out how to install a barrel recoil lug and bed that into the stock - obviously needs doing before the front sight gets done.