One sleeper of a wildcat is the '375Taylor' loosely based on a 300WinMag opened to 375cal ... I suppose the 375Ruger makes it redundant.

The 375H&H is an extremely versatile rifle, and can be loaded to 375Win levels if needed.

Likewise the 458WinMag in a 9lb rifle shooting 350gr Hornadys at 2470fps will do just about everything you'll ever ask of it.
Cheers...
Con