I'd go Azodin. Superbolt bolt is garbage (IMO), and can't be replaced without a whole new backblock due to the stupid twist-lock design. That and the feedneck on the Superbolt doesn't fit gravity feed hoppers, and isn't threaded to easily replace.
Also, the Azodin has that nifty retention system built into their barrels, so you won't suffer rollout if you cock ahead of time with imperfect bore size.
You can use any 2K+ backblock w/ 2K+ bolt IF you don't mind the gap between where the P-block body end and the backblock begins (some people think it look neat, some people think it looks ghetto). If you dislike that gap, then you're only option to replace the bolt would be to drill the stock backblock for a pin and use a standard EVO length bolt.