Further suggestion on your wildcatting--

The 375 seems close to the 9.3 in ballistics and function.
Ever consider necking the diameter down to 338?

The bullet availability would be massive, and futher reach with tough lighter weight bullets 210 gr-225 gr at higher velocities would be possible. They would be harder to regulate but could possibly extend your range for plains game hunting.

Is there a flanged hull out there for the 338 bullet?

There is the 333 Jeffery and the 318 WR. but they are unusual bullet diameters. I do not know their water capacity.

Hmm! A 338 DR. Sounds like great fun