Poor Seal of Head Gasket Year After Rebuild

Last year I finished the 29 six cyl rebuild and a 50hr run in over several weeks. Re -torqued 3 times. Then moved on to other areas of car restore.

After a year sitting, started readying the engine this summer for install. Changing oil and coolant, but re-torque not yet done. With plugs out I spun over the engine on the starter.This caused water to run out of the downdraft carb. With exhaust manifold off, find about 3-4 tablespoons of coolant is ejected from the exhaust port of #4 cylinder as the engine rotates. 

With head removed no visible points of leak. However head bolts felt more like 25lbs torque the 55. 

Examining the block surface, I see pock marbling along and under the cylinder chamber gasket area. Like a trail of minor rust potholes running between one of the small coolant ports along and under the cylinder gasket. Not pointing at this area as the main culprit, but its a good start.

I was researching a copper sealant (Copper Coat) to better keep this from happening. I've also read of the use of a high temp black RTV as a top layer around all fluid ports of the block and head surfaces. The head gasket is coated twice per side with Copper Coat and allowed approx 20 minutes to tack up, then installed. Everything torqued to ~50lbs and left for 24 hours, then re-torqued.

For poor sealing head gaskets, what are you guys doing?