Cylinder leak down results have me confused
 

Hello I have a 1999 Ford power stroke. 280K miles. Cylinder #1 failed CCT , shows 380 psi dry compression 6 crank revs. Other cylinders are 420-440 psi. I ran a leak down test on #1 and got bad numbers 80% leaking. No leakage from valve train. No air from oil dip stick tube ,no air in coolant tank. All the air is leaking in the push rod ports in the heads and seems like most is closest to cylinder #1. Normally this would make me suspect piston ,rings or cylinder issues, however my truck has never smoked , has never shown any signs of blow by "very minimal vapor and a ping pong ball will rest on oil fill cap ". I do not think I can show 380 psi with 80% cylinder air loss and see no signs of blow by from crank case gases ? Do u think it's possible to blow a head gasket without mixing water/oil , without pressurizing cooling system, without blowing coolant out exhaust ? Could the push rod channels in my head be where a blown head gasket is pressurizing ? Are the push rod channels connected in the head ? Anyone have any info or comments concerning the lack of blow by yet air coming from push rod channels? Thanks