Have water in oil, cyls 2-6 fine, nr 1 plug wet, water in oil. Suspect it is head gasket but not sure. Do not have place to do head gasket nor tools, etc, so will have to pay to have done by local NAPA or such (use their head gasket set?) Have had work on truck done there, great place, mechanic i former Datsun shop. Est is 525 plus tax, is that reasonable? IF worse case is head cracked, what is real cost for replacement head. Need to go cheap as 73 on SS, so not a lot of spare cash. Thoughts? Have had 78Z for 25 years, used to do most work self, but back no longer accepts such things. Ole machine and I still run pretty good despite age.