Yep. Paint it with a magic marker, scribe the new diameter, and sand to the mark. Bingo, and nice and smooth.

Say Capn'... If you are going to get near or into the pulse hole, you can just fill it with epoxy or JB Weld. Then run an external pulse line to the carb. Sometimes I also get close to the recess for the bolt down screws. I make a little dam, build it up with JB Weld, sand it off flat at the mounting surface, and then use a smaller headed mounting screw. That gives me more "meat" to grind to, or into, as the case may be.

AV8TOR