Just a heads up if/when you go to order a new control panel overlay, your select game button isn't in quite the same spot as the actual 2 slots. So you would probably want to order a 1 slot overlay and cut the additional button hole yourself unless you're capable of patching that hole and redrilling it in the right spot for the mutlislot overlay.
Or if you only plan to use the multicart, maybe just doing away with the select button entirely.
Looks good!