One other suggestion:
Which ever way you go, DON'T try to use a hand drill. Make a suitable fixture to attach the carburetor to the base table of your drill press, and CENTER the bit for drilling.
Once you have the hole drilled, UNPLUG the drill press, and use the drill press head to hold the tap, and rotate the drill press head by hand.
Even a genuine Heli-Coil would have issues if not installed "plumb".
Do it right, the first (and only) time.
Jon
