Johan is correct -- the 10x68 would be pushing the limits of size in that action - which is really a small ring mauser type action.

I have seen wonderful custom rifles based on the BRNO "21" in 30-06 and using the original stock, which for such a light rifle must bite a little bit. BRNO 21 traditionally have long throats that allow a 8mm bullet to be seated quite far out and one can get very nice velocities out of them. I find that when loaded heavy they tend to kick a little - but they are wonderful "carry for a long time to shoot once" rifles.

I have found that the BRNO ZG-47 magazines a a few millimters longer then the 21 or Mauser 98's and the ZG-47 (a large ring) were used by BRNO in the 10.75x68. ZG-47 make a better platform for larger rounds for those two reasons.

and by the way -- if you are selling that old stock - give me a pm here in Canada please