Well, I went ahead and welded the new surround to the hood. Again, I made a series of tack welds, a few inches apart, from one end to the other. I then connected the tacks, working about half an inch at a time until the entire piece was welded in. After a bit of grinding, to smooth thing up, I spread a coat of plastic body filler over the entire seam. There were two, very minor, low spots that required a second coat of mud. At no point is there even an eighth inch of filler anywhere on the hood. Just a thin skim coat. I hit it, again, with the epoxy primer and dusted on a guide coat from a spray can. For those unfamiliar, the guide coat aids in the final sanding, prior to paint. The area is sanded with blocks and long boards until the black is gone. If any remains, then additional work is needed. It might be just a few more coats of primer, some spot putty or, worst case, some more body work. I think I'll get by with minimal extra work. It seems pretty smooth, as it stands. I'll bust out the sandpaper and blocks, later today, and see how my handiwork looks