Here in Pa we drain the block, manifolds and blow out the hoses. Then close it back up and dump in
a 50/50 antifreeze mix. We don't fill it just about two gallons total between the block and exhaust.
We spray wd 40 on the intake and valve covers. I leave off the dist cap and put in a paper towel and cover the dist. I've had condensation under the cap before.
We also take off the carb, drain it and store it in a plastic bag in the garage. Like you, we have all exhaust and manifold openings sealed off.
Oh and change the oil, grease the jet and universals. In other words purge all the water and contaminents out of the system you can.
I've been doing it this way since 1977 with no issues.
