I got the key from Mike Penland. and the puller from a site on ebay. When I had the flywheel off i measured the keyway and found that a wider key was the same length. I calculated how much I would need to remove from the top side and then removed the same amount from the oposite side on the bottom. I was going to have a friend machine it on a milling machine but I was too impatient so I did it the old fashioned way with a flat file. As near as I could tell with my timing light it came out real close to 6 degrees. The flywheel doesn't move back and forth like it did with just cutting one side. We went to Little Sahara Utah last Saturday and the power was improved. The biggest change was in fuel economy I used much less fuel than the last time we went down there. A good change for not a huge cost.
It would be wise to get new gaskets before you make the change. Both of mine stuck to the surfaces and couldn't be reused, and the local dealers didn't have the gaskets in stock.