HOW TO FILL A DRY COOLING SYSTEM WITH NO AIR LOCKS

Probably not a problem with that thermostat. Not really an issue with "regular" flow systems, only the newer systems with reverse flow have trouble. If you really want to be sure, replace a manifold heater fitting with a 6" piece of pipe and a bell reducer at the top, you'll need a threaded cap for the bell reducer. Or do like post #9.