nothing beats an original mauser, and some were actually chambered in 9.3x?? in the first place. after that, the Model 70 is likely the best immitation. the CZ is cheaper, but I've heard/seen some issues with them, the Ruger is generally a cheaper Winchester, so skip it.

I would give yourself at least a 22" barrel, probably 24... in a rifle of that caliber, I would skip the thumb-hole, but mostly just on preference.

the barrel length COULD be addressed by using very fast-burning powders, but even at that, you would have pressure issues and likely some iffy pressure spikes. whatever you do, keep us updated!