Getting Rochesters set up correctly takes time, some amount of bravery, a lot of patience. Read this article.
https://www.inliners.org/tech/tech4.htmlPat was Dyson Racing’s head crew chief for many years and one of the smartest tuners I have ever known.
As for the Unisyn, get a new one. You defiantly need to have both carbs taking in the same amount of air at idle and the unisyn or the fancy unit used on Weber carbs is the way to do it. Otherwise, you end up with the carbs taking in differing amounts of air at idle. So much so that one carb goes into off idle circuit, leads the other carb into the off idle circuit, then cycles back to idle and starts all over again.
As an alternative, the carter carbs, especially the smaller carbs like the YF for the 216 motors run pretty well in dual single form.
Another alternative, get a pair of adapters from tom Langdon over at stovebolt engine company and install a pair of 74 Ford pinto Holley/Weber 5200 carbs. Nice progressive two bbl carbs that run great in dual form. Tom also sells the Weber variant, the 32/36 if you want factory new carbs.
