I pulled the head off the T this weekend to see why there was no compression in the #3 cylinder. Turns out it had a bent retaining pin on the exhaust valve, which kept the valve from completely closing. It looked okay when watching with the side cover off, it moved just like all of the other valves, it just raised the valve enough not to seal. I wish all repairs would end up this easy and cheap. While I have it open, I intend to lap each valve and do a clean up. It is not really that bad, much better than I had expected.
The carbon crust in top of the pistons can probably be scraped off with a scrapper, what is the best way to clean around the valves, and the rest of the top of the head. How about the head itself? I don't think you would want to use a wire brush, for fear of leaving a stray bit of wire in there.
This appears to be the tool sold for the purpose. It's available tons of places.