Any of the short action mag cartridges will work. However, due to the action and magazine being a Mdl70 short action, you will be limited in performance on the 6.5 PRC, WSMs or SAUMs due to having to seat the bullet so deep.
You could check out the 6, 6.5, or 7 Sherman Short (SS) or Short Tactical (SST).
On a Winchester push feed you can go to any cartridge that will fit the length. The bolt face on those can be reduced with a bushing to take a smaller cartridge rim diameter. So, the sky is the limit for a little extra cash.
I don't recall them making any CRF WSSM's. That would be a bitch to get to feed.
Poor feeding Winchesters was half the reason the WSSMs faded away. The other half was how Winchester made the brass. A Browning 25 WSSM with better brasss is a sweetheart rig.