You need to put in less fuel as the others have said. The only thing the excess fuel is buying you right now is detonation protection, which is probably why it was set up that way in the beginning. Now you need to start jetting down, also as was said test the vacuum under the carbs to see if you need a lower rating power valve. You either have 2 or 4, depending on what carbs you have.

Sounds like a good tuner might be able to help quite a bit.

R.