I have several ways to repair those, all involve epoxy putty of one type or another. Tig Welding them is dicey at best and the final shape will always show signs of the weld. For that matter so will putty but it's a bit easier to cosmetically hide when done. Repair as small an area as possible, just enough to fill the entire hole level, put clean tape over the bottom so it doesn't bulge out and cause a bump on the mounting surface (future vacuum leak). Finish by hand with small files and sand paper to blend, tap some silver paint over the area overlapping the hole area with stippling from the tip of a small paint brush (like for plastic models). Use a satin finish aluminum colored paint, mix it in with flat aluminum paint until you get the sheen close. This procedure is best done AFTER the rest of the carb is restored. Takes a bit of time and practice and It will never look 100% perfect, but you can get it close enough so that it won't be easily spotted.