I have an alternative suggestion, but for the same reasons.

Look for a good Pommie black-powder double in the .450 to .500 range. Plain-grade Birmingham guns with a bit of honest wear generally escape the attentions of the collector, and can be acquired for a few to five grand at most. Graeme Wright's recipe book takes the mystery out of shooting them with light nitro and jacketed bullets, and the ballistics are certainly adequate for medium game up to elk/bear on the eastern side of the Pacific. Recoil is low, pressure considerably lower than the BP service-loads, and case-life correspondingly long.

I started out this way, with an AH .577 and a Tolley .450. Still own those rifles, marvellous stuff. Might even shoot black-powder in them one day! (Naah...)!