Are the carbs the 2G or 2GC version...the 2GC is the larger version.. Years ago we were stuck using the Rochester 2bbls in circle track racing.. The best mod we ever found for them was buying the tapping tool to convert the jets from Rochester to Holley! Finally able to do some tuning on the buggers!! I think Speedway Motors might still sell one if jetting becomes an issue.

I would try a PCV valve in the breather tube--without one it's likely that crankcase pressure could be forcing a lot of oil vapor from the lifter valley through the center carb????