Go to your local airport with a jug and buy 100LL avgas, it's blue. The green 114 would be bad because of the high lead content. The red 80 also has a high lead content. 100LL avgas isn't that high of an octane, aviation gas is rated on a different scale than car gas. It is designed to be used in air-cooled aircraft engines that have usually no more than 9 to 1 compression ratio. We use it in all our small engines, weedwackers, chainsaws, antique tractors, etc.
You can leave it set without adding stabil and it won't varnish everything up. My small engines can set a year and start on the second pull. Have at least a couple hundred hours on a K301 using it and took the head off this winter, looks fine.