Im leaning more and more towards a factory new blue head.... All the grey heads were built prior to 1990 and so the only was a sane person could fly behind one is have someone tear it down, inspect it , reseal it, install the ceramic water pump seal and viton crank seals and even then you have to be careful how you operate it or else you could shock cool it and seize it up....
Most all the grey heads are around 3000 to 3500 and no real history on them, how many hours etc. Maybe I guy could get lucky but if it failed you would then beinto it way more than just having bought a new blue head to begin with I thing. I reallize even a blue head can fail but I think I would have a better chance....with one....still learing all I can about them...