Either remove the flip up and replace it with a dovetail blank or put on a taller front sight.
I bought an old Marlin 39a that was like that but it had a rear tang peep. For the life of me I could not figure out how anybody shot the thing. I figured the tang peep may have only been used only for long range because the rear leaf was in the way also. The rear leaf was not a folding one though so all I had to do was replace it with one that folded. With your receiver mounted Williams, you can't even really do an either/or kinda thing because it doesn't fold away like a tang peep.
