I used a 1/2" rotary/carbide bit that was about 3/4" long with a rounded end on a 2" stem to do the ports, which worked nicely because the port openings in the gasket are 1/2" radius so it worked perfectly to shape them.
Used the same bit to cut into the top of the guide were all that meat was. Then switched to a 1/4" conical rotary/carbide bit with about 6" of stem to shape the rest of the guide and get back into the sides and short radius.
That's it as far as tools. They worked out nicely. I'll have to get some pics of em. They're at work right now.