Ravenwolf,
Keith developed the 338-74 Keith cartridge in 1979/71, and wrote about it in his Gun Notes article in Guns&Ammo in August 1971, as well as dec. 1977 and dec. 1979. I'll send you a PM on this.
With Nosler 250 grains bullet he got 2711fps; 49950 pfs pressure.
With 275 grains Speer: 2580pfs / 50220 psi pressure.

Here is a drawing of the cartridge:
http://www.again.net/~steve/jpg/cd33874keith.jpg

I have not found anyone stocking reamers or dies for this cartridge, but I haven't looked real hard yet.
338x74R