I just use a carbide bit, or even a drum sanding roll and the dremel to open mine up. Yes, be careful not to get too close to the pulse hole, though if you do, you can plug the pulse hole with JB Weld and plumb an external pulse line to the carb. Another area that gets close is near one of the mounting screw bosses. It can get real thin for gasket sealing there. What I do is use a screw and a collar in the hole to protect it. Then fill the area up to the collar with JB Weld. Scrape it flat with a razor blade before it sets up completely, then block sand it flat after it is hard. This gives more gasket suface area in this thin spot.

Hope this helps, sorry no pics. I believe there are some pictures on this page that are similar to how I do it:
http://www.shark-racing.com/Ingles/T...acaoMoting.htm (Be patient, it is slow to load.)

Good luck,
AV8TOR