RE: H-9 Showtime .50 engine?
Yes a Saito 82 would be more than enough at sea level. If you fly at 5000' altitude like we do in Denver, you have to install larger engines because of the power loss at altitude. The Saito 91 on my Showtime 50 provides adequate power for most aerobatics, but it is not overpowerd. I suspect it would be marginal for 3D at this altitude.
Frank