The rib design is not conducive to many sights. Honestly the Maxus is a great shotgun but was ill designed for any type of aftermarket sight. Even if it was factory drilled and tapped Browning uses a proprietary base that only allows for a scope or a long tubed red dot.
I dont like d/t aluminum receivers unless there is an insert or bushing that distributes pressure to the receiver. Look up my posts regarding the Maxus for my woes regarding sights for the maxus.
I suggest trying to find a fiber optic sight that will fit the lousy rib design and keep the gun simple and light. Good luck