anyone know of an alternative to MSD cap

Looks like you slotted the distributor housing for ignition mounting plate adjustments. Guessing for mounting a pertronix 3?

I wish, but it's coming some day just for the heck of it.
Just slotted the plate screw holes so I could adjust the rotor phasing because I run quite a bit of initial advance as well as around 52 total with vacuum and didn't want the rotor wandering off.