MJD, that is a good question.
Doug Galbreath of course handles Cyclon. You can also deal directly via email with Aleksnadr Kolmykov of Cyclon. Galbreath was less expensive than going through Mr. Cyclon, but I had to wait much longer going through Mr. Galbreath for a 1cc engine.
FORAs..it used to be George Cleveland of GRS Models but I'm not seeing any search results for them. I've heard of a Canadian outlet and should get more detail soon.
Believe it or not, CS [Chinese fame] list a F2D engine but they only work with retailers. In this case, Bill Hughes would be the contact and I believe he is still actively doing business.
Rich Lopez who writes the CL Combat column for Model Aviation is an excellent all around source of knowing where to go for everything. I haven't contacted him yet.
The guy who handles Profi ..Jim.......Booker. He was the guy a few years ago. I just don't see Profi listed in the win column locally, but that can just be a regional bias.
Darren Albert is another name . He bought up Kustom Kraftsmanship and he is very active in the sport.
I'm "working" at it..but the usual sources always seem to be sketchy. To this day, I do not know if any of these combat engine builders offer CL Speed versions of their basic engines or not.
My hope is that with normal 1/2A equipment a .15 powered plane will be a step up from the .061 powered planes. Not just in actual speed but also apparent speed.