I've ported a couple of sets of heads. I haven't messed with the chambers, primarily because I've wanted to keep up compression and didn't want to screw up the valve seats. I've focused on the runners.

If you attempt to do any of this, invest in one of these:
http://cgi.ebay.com/ebaymotors/ws/eB...tem=2455198217

Having a rotary tool with a 1/4" collett is a must. Air tools would drive me nuts for the amout of time it takes to port.

At first, I bought one of those sandpaper dowel kits, like the standard abrasives kit. It worked great, but I when I used them to remove lots of material, they went fast. These did work wonders after I had the casting removed and needed to smooth and polish the surface.

Then I tried several kinds of stones, but they are horrible at caking up with aluminum. It makes the stones almost useless. I found one stone that worked better than others, it was red and very course. The finer stones would fill with aluminum almost instantly.

At this point, I discovered the rotary file. This was exactly what I needed. It would cut easily into the aluminum and quickly removed the casting material. I found a couple differnet shapes, one with a flat head, and another with a round head. These cut my porting time down a great deal. Like these:
http://cgi.ebay.com/ws/eBayISAPI.dll...category=42249

That rotaty tool with the foot control and flex shat using 1/4" bits worked great. A standard Dremel with 1/8" bits would be a big PITA to use for this amount of time.