I don’t think you could simply rechamber it for a PRC. I think the WM has a longer shoulder length than the PRC. Do you load for the WM? I’m getting 2860 out of mine with the 225 ELDM and I think I could get a little more if I wanted. If you want to simply rechamber your rifle you could probably try the 300 RUM.
I haven’t ever heard of a +P rifle cartridge.
Mike