so i bought my first ar-15 last year, for a "fun to shoot", S.H.T.F. and varmint rifle. after mounting a scope to the handle i was shocked with the way it looked and felt with the scope way the hell up there, and noticed I made the mistake of getting the fixed upper carry handle, i now know i want flat top upper with a bull barrel and free float handgaurd. so what would be the best choice / most cost effective; sell my upper and buy the setup i want? or sell the whole ar-15 and start over?