The easiest standard caliber for conversion would be the .300 Win Mag, but there might be a problem in the magazine, since the .300 Wea Mag
OAL is about .26" longer.
For practical purposes, the two cartridges are not much different, but on paper the Wea Mag puts out an extra 300 fps. Naturally, there is also extra blast and recoil. I don't know whether, in the long term, that extra push might cost in terms of wear on a rifle not designed for the more powerful round.
Jim