Tri power?????????

You believe it is running rich AND might have a vacuum leak. With more than one problem to track down, you might be ahead to have a Holley carb guy look at it. Without some experience, multiple problems at once can be a bear to unravel.

But for one thing, if you think it is a bad power valve, most auto supplies will have a 6.5 in stock for $10 or so. Throw one in, just to see.