i have a well used gms 76 that is a great performer.
unlimited in most 60 size aerobats. BUT!

like big ed said. you better be ready for a long breakin period.
and the low end needle is very touchy.

once the engine seats in provided you break it in corectlly
it ll be fine. mine will idle all day and never misses.
low end is around 5/8 turn out