I do not recommend trying to bend the tabs while fastened to the carb set. The soft metal will easily-break!
Probably the safest way to bend any steel parts is to remove them from the die-cast pot-metal carb bodies. Take lots of pictures, and make some notes, to help you get everything re-assembled. Clamp the piece into a vise, and use a large adjustable jaw wrench, like a Crescent wrench, a longer one provides you with more leverage. Make sure that you know which-way you need to-go, bending it. This process is 'cold-setting,' and you probably don't need to move things much. Try to determine before everything is apart, what direction you need-to bend it, and how-far. If the item cannot be easily-clamped in a vise, you might find it necessary to use two Crescent wrenches.
Here's a technique for getting things bent properly. Use a coil of baling wire, clip-off about a 4" long piece from the roll of wire, and bend it to the shape of the bracket. Now you have a template to use, to compare how-much you've bent the tab. You could also use a scrap of solid copper wire, but you better use at-least a 12-gauge wire, because as-malleable as copper wire is, it won't hold its shape for purposes of comparison to your bent bracket, if you use anything of a higher numerical value/smaller diameter (gauge) than that.
My experience with threaded fasteners under light loads like these screws, is that you would have to be really working at it to strip one of them. They don't have-to move very-much so there really-isn't much torque on them, nor is much force needed to move them in/out. I'd use a magnifying glass to carefully check the screws' threads for deformities.
I dunno where you live in Miami, but I've found a good selection of metric fasteners at the Ace Hardware at 6448 So. Dixie Hwy. So. Miami 33143 by Sunset Drive. It's just-north of where the Snapper Creek Expressway (SR 878) dumps-out onto US-1, north of the Dadeland Mall, it's in a strip mall building set way-back from the road. They have metric stainless steel stuff too, I'd buy some SS 4 mm machine screws for the float bowls, get 'em in allen heads. You could swap-out the CV diaphragm cap fasteners too, in-fact, bring one of each, and swap 'em all out!