Hmmm, Seems my cab is a bit smaller, but not by much.
Mine is roughly 62cm x 62cm x 39cm. And nil fancy connector plate, just a simple molded metal plate large enough for two connectors and held in with 6 screws . Also my cab is covered with black marine carpet all over the top sides and back hence the measurement inaccuracy. Front is just painted black with the grill.
I doubt the minor size difference in the cabs would affect how it sounds with diff drivers too much. If it were me I'd be disconnecting that control and getting a nice new set of Eminence Legend drivers for your cab.