I have a CZ .458 that I have come to know well. It is marked:
458 LOTT/
CAL. 458
WIN. MAG.
So, at least we know what CZ thinks about the interchangeability! Having run a few (!) .458 WM rounds through it, the accuracy is not any worse than with .458 Lott (POI is lower, of course)...but the rifle is not a tack-driver with either, and 150m is really the end of its dependable range (not bad, given its intended use).
Thre are an awful lot of rifles in Africa that were .458 WM and have been converted to .458 Lott (in theory; they may in reality be .458 Watts). But when built on a standard-action .458 Win Mag typically the box magazine must be changed for a longer one and the receiver must be machined. As stated above, the process is must simpler if you have a magnum action.
Probably a good idea to ream the chamber to accept a 2.85 case (most available reamers allow this easily), as some ammo manufacturers use the Watts dimensions, and reloaded brass doesn't have to be trimmed as much.
By the way, Jack Lott had a 22-inch barrel in mind when he designed the cartridge, so having a "true Lott" may cost you a barrel shortening, too, with the resulting replacement of the front sight and re-regulation to chosen ammo. And the cartridge can be hard on stocks, sights, swivels, and magazine floor plates, which all can fail under recoil unless attended to. Ask me how I know.
More info here:
http://www.calpappas.com/id11.html
http://www.go2gbo.com/forums/index.php?topic=29621.0
http://www.shakariconnection.com/458-caliber-rifle.html