The reason I cut it at 1.700 is that is the length that the 44 Ballard Extra Long is cut at before opening it up. It's based on the .220 Swift, but should be close enough to get a safe starting load. Plus it left some OAL room for different bullets in the AK mag.
A .41 or .357 would be a good choice too. I just grabbed a .44 bullet because I had them on hand.