Finally, I used this flap disk on an electric grinder to clean the weld up somewhat. This one is going to be covered, so I'm basically just wanting to make sure no weld is sticking up high enough to interfere with the outer patch. Once it is ground down good enough, I cleaned the whole area with mineral spirits and then sprayed on some self-etch weld-through primer. Final picture is the original patch over the original hole. It is really close to fitting but need just a little more grinding. But, its dinner time and I've had about 1 too many beers to tackle any more on this patch that's going to show so I'll finish it up one night soon
Hope this helps someone that is just looking for a clue as to what is involved, and the tools used.