OK, I located my Lyman #49.
The 375 Win pages include 2 jacketed and 2 cast bullets.
For each bullet, 6 or 7 powders are listed.
The bullet that meets your description is a 249 gr cast.
Fastest & potentially most accurate load uses IMR-4227.
Min is 22 gr @ 1617 fps. Tested in a Win 94.
Max is 26 gr @ 1925 fps.
Please buy the book and be sure these numbers are correct !
Be Safe and Have Fun !
-steve