That's one of 3 (or four?) select-fire Type 3 AKs imported by Sam Cummings circa ~1960. The CIA requested two, and Sam seeing an opportunity didn't stop there. So that's one of the first if not the first AK pattern rifles in the US. It's not clear what the gun would have been designated in Polish service, but it's probably a kbk AK or pmK.
The guys at Circle 11 factory really knew what they were doing, too as that gun has the slickest bolt of any AK I've ever handled, period. Puts even Finnish guns to shame.