Unleaded gas doesn't follow the same rules of thumb that most of us oldtimers learned- - - -"Tan to chocolate brown" for the right mixture. The lead additives in the older gas were what gave plugs their distinctive color. Unleaded goes from white to sooty black for a too-rich mixture with very little variation in between.

I'd suggest getting a few Holley main jets (they're cheap and plentiful) and running a threading die over them to make them fit the Rochester carb thread. Then you can take a set of number drills and a pin vise and make up a set of experimental jets in various diameters to tinker around with the mixture. Once you find the sweet spot, you can either leave the test jet in place, or modify an OEM Rochester jet to the same size.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!