Soon enough I will be getting a Grizzly pistol lower and have several ?s about pistol uppers.  I want to get a 7.5" upper.  What makes are out there?  Who's the best for my money?  I would like to spend around $500 total for it.  A2 or A3 upper?  If A3, with or without carry handle and front sight?  I don't know how good iron sites work for an AR pistol.  After reading some posts, I figure I will have to replace the recoil spring with a longer 1911 spring from wolf.  If the best deal is a Model 1 sales upper, will I have to get the chamber polished for reliable feeding and extracting?  Anyone besides Oly Arms make an upper that has an internal gas system without the tube sticking out from the back of the lower receiver?  Is Oly Arms making preban pistol uppers that I could use with the Grizzly lower?  Thanks for any help.