EERRiiicchhhh.. (Brake sound)

You really don't want to try to drill out the carb spacer. There is a VERY good chance the drill will catch, and destroy the spacer. I just use a sanding drum in a Dremel tool to ream mine out... only takes a few minutes, as the material isn't very hard. You want the spacer to have the same size hole as the outlet of the carb. Also, if that makes for a step where the spacer fits to the intake port, you need to blend the step out as it will be an obstruction to flow.

Good luck,
AV8TOR