Well, I shoot the Lyman 265gr. GC bullet patched in my 375X338 with exceptionally good results. I size it to .375, patch with 9# onionskin, lube with paste wax, and size to .375 for a final diameter of .376 with the springback. Don't know why it wouldn't work in your 375 as well, though something lighter would go faster. I used to have a TC barrel in that round, and it worked well with this bullet but I hadn't learned about paper patching yet.
Added on 10 Mar 2010:
I just remembered, the Lee 250gr. bevel base made for the 38-55 works well too. Just size to whatever you need. And I noticed this morning that Dick Dastardly from
www.biglube.com has one that looks good as well, and it's a 6 cavity mould so you can make a bunch in a hurry.