Intake cross over blockage or not ?

I've read a few different opinions on cross over blockage. Has anybody had plug fouling or cold weather driveability problems? I drive my car from May to October if weather permits. October is pretty frosty some mornings. Once the engine warms up to temperature you shouldn't notice any difference blocked or not blocked should you? I do have warm fuel problems the same as everyone else, so thought this may be the answer. 1969 340 engine with thermoquad and oem intake. Do I block or do I not block?