I also have a .375 H&H mag pre-64
So I might make some bullets in that caliber.
Have you ever used the Woodleigh bulets ?
I shoot then in my 375 they are 235 grn.
I have also loaded some rhino solid shank 270 grn. but not hunted with them.

My favorite big bore is my .500 Jeffery

Cheers,

André