The reason I asked is I also have a set of J heads that was giving me the same issue. No compression and leak down sounded like exhaust. It was building crank case pressure and it had the squirts! Pissed off I had no choice, tare it down. I was hoping it was the head gasket too. but it wasn't swappin spit with the oil/water witch pointed me to the valves/rings. Pulled the head and all appeared to be normal no bad gasket. keep in mind the EGR port in the steel heads have threads in them from the intake and exhaust (small hole, U-shape hole) next to #3 & #5 exhaust valves. Spark plug told me lean. It had fried the exhaust valves and collapsed the lifters. Even if you seal the threads on the intake bolts its possible to get a lean burn condition over time. I want to fill those stupid holes but reading more about them they do have some purpose after the egr is gone other than a carb nut catcher. Im gonna block them.
