Hi!
I have zero experience with E-85, but a lot of time running straight alcohol engines. Alcohol has a MUCH lower specific gravity than gasoline. Since the 14.7:1 air/fuel ratio all engines need is figured by weight, not volume, you'll need to re-jet the carb for a lot more fuel flow. When my Dad started running the family race car on alcohol back in the early 1950's, Carter Carburetor reccomended we increase the cross-sectional area of the main jets X10, or approximately 3 times the gasoline jet diameter. That was for full-throttle work on a racing engine, but I'd guess a main jet diameter twice the gasoline jet size would put you in the ballpark for street use. I do know a Ford/Holley 2-barrel on a flathead V-8 runs too lean on alcohol, even with the jets removed. There is too much restriction in the internal passages of the carb. Stromberg 97 carbs had a less-restrictive fuel flow, and could be jetted rich enough to work on straight alky. I have no idea if your Rochester could be jetted rich enough without increasing the size of the fuel passages downstream of the main jet.
Jerry

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