msturg
+1y
i've figured out two good ways it seems that most people do this. One is to use Fusor Seam Sealer to join the fiberglass and steel, screw it in to hold it in position of course, but don't use bondo to fill gaps, just use a body filler to skim it.
another way, is to use the grant kustoms pan as a mold. cover it with wax paper or ducttape and make a fiberglass pan from the mold. That's the way i'm considering doing it.