It is slightly possible there can be a galvanic corrosion problem between the stainless coil and the Zinc/Al body. Also the stainless coil and the brass fitting..... and all three in close proximity. Gas always has some water in it which will act as an electrolyte. Not to mention the cost of the tools, drill and tap for one helicoil.
I think the emphasis here would be on SLIGHT POSSIBILITY of galvanic corrosion.
But I would have to agree on the cost. That and the fact the end of the tap may have to be ground off to get the threads correctly cut for a helicoil without bottoming out in the hole.
Like Jon (carbking) said, unless that was an extremely rare carburetor, it wouldn't be worth repairing.
I agree with JW51, that a real caveman fix would be to epoxy the fitting in place. I have actually done that on a diesel fuel return line fitting and it's been working for years now. It was a fitting where the tube was pressed into place, but had worked loose. That fix is still in place after many years. I recall that I used JBweld on it.
