The Aimpoint is not a precision optic.  The dot covers roughly 4 inches at 100 yards.  Not the best choice for “small game” hunting, IMHO.  

BTW, I've hit steel targets at 200 yards with an Aimpoint.  However, I'm shooting at 8"x8" or bigger steel.

A traditional magnified scope, unless made specifically for the carry handle, will sit WAY too high (again, my opinion).

Since the Aimpoint isn’t the best choice for your application, I’d either swap the upper receiver for a flat top or get a carry handle-mounted scope.  If you want this type of scope, the ACOG is the best quality out there.  There really isn’t a lot of in between; most of the CH-mounted scopes either suck and are cheap, or they are high quality and expensive.

If the cost doesn’t drive you away, grab an ACOG.  

I think you are better off swapping the upper receiver for an A3.  Call Eagle Firearms and get a RRA upper for $88.  Go to your hometown forum and ask if anyone local can swap them for you.  It is an easy task with the right tools.

HTH.