Despite all the posts about cartridges longer than ?X57mm, with the cutout in the OP's receiver for the thumb while loading from stripper clips, some measurements are in order before planning on using that action for cartridges longer than ?X57mm.
There's a wealth of ?X57mm out there to consider from 6mm Remington, .257 Roberts, and 6.5X57mm through 9.3X57mm.
There are also plenty of ?X51mm cartridges to consider as well: .243 Winchester, .260 Remington, 7mm-08 Remington, .308 Winchester, etc.
I'd enjoy seeing the receiver used for something like a modern full stock (Mannlicher style) carbine with 20" barrel in 6.5X54mm Mannlicher-Schoenauer. JM2C.