RE: What about GMS 76?
GMS engines, like many others, run great if the carb you get isn't leaky or has a mis-drilled spraybar. My first and I hope only experience with a GMS engine demonstrated both issues, and that was not unique according to field reports I've found scattered throughout the forums. So if you are thinking dead-nuts reliabilty check it out thoroughly on the bench first. This was with a .32, and although I've seen/heard the same about other sizes you may want to check that out first.
MJD