Well, I've just been down the path you are on if indeed you are a custodian of a dreiling chambered in 8X57R/360. Actually, if you use the lengthy version of 38-55(I think Starline has them for say 16 cents?) easy to convert but are just a few mm short & you just have to extend the bullet out. Other than that you need some 360 2 1/4" brass, but those are typically converted from something.

Cheers,

Raimey
rse