Wanted to give an update. Since I got my stamp finally I went ahead and bought another barrel to see if it made a difference and it did.
The first barre I had was a KAK 8" 7.62x39 using a pistol gas system. After taking some rough measurements with a caliper I concluded doing the install via superlative arms instructions the gas port on the block would barely meet the gas port on the barrel, with an already small port size I knew this would be problematic for cycling.
I didn't have another pistol length barre to compare to know if the superlative arms op rod length was wrong vs the pistol gas length standards
I found a website that sold 7.5" 7.62x39 melonite barrel: cobra Tactical systems that actually listed the gas port size: .910", I figure I order this barrel so I don't have to redrill my current barrel and gas port size would be big enough to give extra room to meet the gas block and I can always dial down if need be.
Turns out after I had both barrels side by side the KAK industries barrel to the shoulder and gas port is ~.05" shorter.
Seems with a gas tube this difference might not make a huge difference but with the piston it does.
So I guess if anyone is trying to use this combo in the future they can reference this experience.