The GEW Length Mausers will work with some modification with the 375 H&H and also the 458 Winchester. The 404 Jeffery and the 416 Rigby can me made to work, but the magazine has to be modified extensively or replaced with a larger one. This can be quite costly.
The CZ 550 is a good one to start with too, but I understand CZ is shooting themselves in the foot by discontinuing most of them.

GEW length military Mausers are my all-time favorites, but they are not made as magnum length actions. As I said they can be used, but the work needed is extensive. The famous 416 Rigby used by Harry Selby was made on a standard GEW length action.