OK Simmons are not all that good. Never seen one hold up too well to any kind of recoil.
Next rings. You are going to need tall or extra tall rings no matter what. As the stock of an AR is in line with the bore of the rifle. I tried medium rings on an AR when I first started building flattop varmint uppers. I had to smash my pudgy face into the stock so hard it hurt to get a decent sight picture. Maybe if your head has been shrunken in a jungle somewhere you might be able to use low to medium rings but, if you have an average sized head go with tall to extra tall.
I am just wondering why you spent $750 on an upper and you are putting a $70 scope on it. You could have gotten a upper for less and spent more on the scope. Or built the upper and gotten a better scope.
My advice is don't buy the simmons you won't be happy never seen anyone happy with a simmons. Save some money up and get a better scope. Even a $200 mueller is head and shoulders about that simmons.