Im running an a14 with sss 510 su carbs, I like it alot. Great motor, only bad thing about them (if your selling it) is the price.
Around here ( northwest usa) an a14 is cheap, couple hundred bucks, 3 maybe 5 for a verry good example, the su carbs are 100-300$ used, a series su manifold are scarce, but around. 100$ can usualy get one.
No one saying your motor isnt good, great combo, but its not a "race motor" such as a gx, wich got closed chamber big port heads, 4 into 2 exaust manifolds, su carbs are just another thing they got. Not the only thing.