I agree with GD on this one, the stock class should be a step up class not a pro class. I know its not officially a pro class, Except at nats, but the good guys should want to step up, not dominate. Win/loss levels are nothing unless you progress and race better racers.
If you are getting 87* after 7 minutes, is the esc hot during this? If not then you are about right, but Might could go higher gearing.
I go by three rules for brushless,
1. If motor is hot, ESC is cool= undergeared
2. If batteries or esc hot, motor cool= overgeared
3. All warm to ambient=happy setup