My Hodgdon book sez 44.0 grains of either H4895 or IMR 4895 with a 180-grain bullet results in 2,600 ft/sec at 50,000 CUP.
FWIW, while I've mostly used 4064 through the years, I fairly recently found that H414 gave best results for both velocity and tight groups.
The 180 oughta be a good elk load. I've always used a 150-grain Sierra for deer. While you can drive the SPBT a bit too fast, the flat-based spitzer won't blow up on a close-range shot.