Those engines have had open exhaust crossovers in the intakes for decades with no negatives anyplace. Most like flooding in lieu of "boiling over". That comes from using over the counter parts, which are low quality and never the right parts. Compensating with a low float setting is not the answer, as fuel level in the bowl effects the fuel delivery to the engine (tune).
Blocking off the crossover(s) also create tuning issues, as the intake will eventually heat soak anyhow, but it just takes a LOT longer, and in really cold weather it will run very poorly, and even "ice" up.
Tuning should be done to achieve best results in all areas, instead of chasing a meter around. I'd put a piece of tape over it, tune for best idle, off idle, light/heavy/full throttle, then take a gander at the meter to see where your "base" settings are at. A little fine tuning either direction from there and watching the meter is OK. These engines have a pretty broad range of A/F they will tolerate, want and need, as some as just a LOT more efficient than others.
Don't forget distributor tuning, it is equally as important as the carburetor, and will allow for leaner mixtures at light throttle cruise, etc.....Cliff
