circofile.com (for the burrs)
MSC or other tool/machinery suppliers (for the long cartridge roll mandrels).

I've been porting heads/intakes for about 7 years. This is what I've found to be the most critical.

1. Speed control. You have this via regulating air pressure. If you use electric grinders (Makita GEO600), a variac is necessary.

2. Correct length and shape burrs.

6" shank and SE (egg) and SC (cylinder w/rounded end) burrs work great on heads and most intake work. A 8" shank is sometimes handy when you want to get deep into the runners of a Vic Jr or Super Vic. You can also get 6", and 12" cartridge roll mandrels. This will allow you to get into almost all areas for the final sand roll work.

Good luck,
Gerald