Preddy, is your cylinder sleeved or bored and re coated ?
Randy, its sleeved. Thats what has me stumped 
That pitting kinda looks like porosity in the sleeve to me. Could it be the beginning of electrolysis from dissimilar metals ?
Any chance your head gasket was letting any coolant into the cylinder? Did you run coolant or straight distilled water ?
Randy
I
NEVER had to add coolant to the rad, but I did add a little coolant to the overflow once or twice. The only time it would push the coolant out of the overflow was when it was beat really really hard. The only times I could remember it doing it was when I let 3 of my buddys drag race it 20-30 times in a row. After that I remember seeing some coolant residue on the out side of the motor.
Looking at the the headgaskets I see no sign of coolant getting through. I always used the 50/50 premix ethylene glycol and distilled water.
