Take pics and notes on the thread depth and the location of the inner end of the brass fuel inlet fitting inside the float bowl.

If you're working on a Holley carburetor (1920, 1945, likely others)

The carb body thread where the fuel inlet screws in is ½"-20. Buy this[/url thread insert. Drill out the munged ca ... A084/]this[/u][/b] thread insert.
Drill out the munged carb threads with a 17/32" drill bit, and tap ⅝-11.

If you're working on a Bendix Stromburg carburetor (W or WW)

This is a more difficult situation, because thread inserts for the required 7/16"-24 fuel inlet thread are much more difficult to get, as it seems. As of this writing, this guy in Australia offers a suitable insert, which calls for drilling out the munged carb threads with a ½" drill bit, and tapping 9/16"-18.

Install the thread insert; it's slotted for a wide screwdriver (or you could probably use a coin) and has threadlocker already on the external threads so it'll stay put.

Grind/sand the outside surface of the thread insert flush with the carb body so the threads begin where they used to, and the inlet fitting's washer will have a flat surface to seal on. Chamfer the hole if you want to do a complete, nice job of it.

All during this repair project, the carburetor body should be firmly clamped to a known-flat, known-square surface (drill press table or as close as you can come). Take great care to drill straight and true. Also pay careful attention when tapping, so tapping chips don't get into carburetor passages. Tape the inside of the carburetor off with painter's tape, for example.

Install the new inlet fitting and verify the position of its inner end (needn't be exact; the float height is adjustable).

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.