I recently purchased a Cz 527 in 7.62x39. In my opinion there isn't any reason to have this caliber in an action that would run 308 just fine, it's a more versatile/practical round. The Cz however is built with the larger cip spec chamber, it will misfire with brass sized with my lee dies. Backing the die off .020" cures this however, I am still going to order the collet neck sizing dies. I suspect if it was a push feed action it wouldn't have an issue. The 527 would be near perfect if it came with an extra saami bolt sleeve and adjustable rear sight. I got ahold of 250 new imi cases years ago so they should last me a wile if I don't loose to many in the field. The s&b brass cased ammo seems to work wonderfully, but I only have a few boxes and it seems to be outa stock on the net, and the local can tire has been out of stock for forever as well.
I suspect in the future it might be better to go with the .300 blackout. I just about purchased a ruger American ranch in this cal, if only there mags/mag release wasn't so crappy. Quality ammo is going to be allot more common and lower priced than the 7.62x39 in a few years, if not already.
It would be full retard to have a smith build a rifle around an old .303 bbl. that's a waste of a decent .303 rifle, the gunsmiths time and ones money.