Ok, so, far as I can tell, these replacement brackets are ready to go.  Got my reworked metal ones in the mail yesterday, and after a little deburring with a file, they work great. I wound up making two versions.  The first is my original bracket that let the wings pivot slightly to bring the weapons parallel.  The second is the accidental change I made, shifting the pivot forward, and locking the wings in place against the legs. This gif shows how much wiggle room the origin