almost any gunstore will have new Rem 700's on the rack...buy a new one with the proper bolt face and magazine setup. Buy one in 7 Rem Mag or 300 Win Mag. These are popular and will require no work other than a barrel swap to work for a 458 Lott.......but, a 458 Lott on a 700 just don't seem right....
a cartridge like that belongs in a Model 70 Classic or a Brno 602 or something like that...IMHO..but what the he11 do I know?