I've been on the AR Forums for a little while and don't remember too many posts on a 458 WM DR. I think JPK was the first in many moons to post about a DR in 458 WM. He's detailed whatever is needed to get the 458 WM/DR going.

BTW, there's an awful lot of blue sky in the velocities listed with any cartridges of old, especially NE cartridges. As with any cartridge/gun comination, your velocities will differ from the old pressure barrels that were used to test velocity.