[jimmytroanoke]

Yes you can do the compression test, but use a remote starter switch or disable the fuel pump if you have to use the key so you don't cover yourself with gasoline from the presumably disconnected fuel lines! Make sure you got the pushrods back in the right place as Intake and Exhaust pushrods are different lengths. If you used the new design GM gaskets they are very rigid and have locating pins so they shouldn't have slipped if properly installed. Never put straight antifreeze in an engine. It has very little heat carrying capacity compared to water. 50/50 min. 70/30 max. Ford had a recall on a few Fseries pickups a few years back that were filled with straight AF at the factory because they were all cracking heads. They replaced the heads on all of them even if they showed no symptoms because they were that sure they would fail.