I like the 450 express.
Most of them (not all!) take .458 bullets - and there's a huge selection of them in weights likely to shoot to regulation *and cheap!*, and there's going to be numerous known-good load recipe formulas that you can likely get components for where you live.

Make sure that you can slug the bores and cast the chambers of whatever rifle you're looking at, and that the seller will allow inspection by a qualified gunsmith or gunmaker, to make sure you will be able to safely run whatever you get.

Cheers
Tinker