For future reference, a 3/8 - 16 tap worked to repair the seat threads.
Since the carb had a lot of pitting and surface rust, after it came out of the dip bucket I hit it with a wire dremel brush. Then after taping off the openings, I coated it with POR15 fuel tank sealer. I've had good results with regular POR15 so we'll see how this works out.
