I'm no fabricator by any means but I did sit and watch while my hood was being cut recently. Not sure if you have done this yet, but for futures references, here's my 2 cents.... With the piece already bonded to the hood, it would seem pretty hard to weld the "lip" around the cut opening without harming the new piece, especially if it is fiberglass. And yes, a strap will have to be in place to tie the braces back together. Would be much easier to lay the piece on and trace it out, then figure the shape of the opening you want, cut, weld, grind, primer,paint, then bold it on. My guy had to work from the top and bottom of the hood and being as careful as he could, there was still some splatter, which wouldn't,t be good on a glass add on. Also by cutting, usually some the "goop" for the life of me I can't remember the proper name for it, it's like a caulk, will be taken away. Just make sure some more is added between the skin of the hood and braces or it will rattle. Again, I'm basing this only from my recent observations.