Makikng this conversion is a big deal. You will need a new longer magazine box with an internal geometry designed for the Lott round, a new follower, opening up of the action (removing some of the ramp, alteration of the rails, cutting out some of the front action ring to allow loading. All of this must be done by a gunsmith who is an expert at getting big bores to feed.

Better to sell this rifle and buy a CZ in 458 lott.

Good luck!