I think I'd stay with the stainless fasteners you have. Fill the threads in way of the shoe and hull with epoxy. As you assemble with the rubber gasket, slather things up with a polysulphide sealant (LifeCaulk, 3M 101).
I've done brazing, but don't really like doing it. Selection of alloy (the rod I have a few of), flux (the stuff in the can with the duck tape over the hole) is always a mystery, plus my torch never seems to put out the heat I want or spread the flame the way I want.