Before spending the coin on a Winl. or Rem. check out CZ. They make a heavy bolt rifle in .375, .458 Mag., 458 Lott, .416 Rigby and .505 Gibbs.
Many African guides use them and for the money they can't be beat.
There is an African guide forum, the web address escapes me. If you can find it, it will confirm what I am saying.