Good topic this, isn't it ?....and your stories, Tony, do make one think about this, that and the other. In my case, with both Gleaming Beauty and ChrisP.'s astral silver "Wilhelm", I was not particularly careful in maintaining the correct coolant at all times, especially so with Gleaming Beauty. Removal of both heads clearly showed very little corrosion damage - sure, there was some - but it was not excessive. The heads work on both cars cost about $1300.00 each car, and that included replacement of valve guides - both types, I think, i.e. Inlet and Exhaust.
Gleaming Beauty had a major problem with water mixing with oil. I had in fact noticed about twelve to eighteen months earlier that green coolant would squirt out from No. 4 cylinder on start-up, obviously with plugs out. That caused a few furrows on my forehead, but being the eternal optimist, I was hoping against hope that with certain measures I instigated that the problem may have been alleviated to some extent - and that's how it turned out. The head gasket leak really showed up when I added coolant (Nulon or Castrol) and the stuff began to search for leaks. Sure enough, it found them. BTW no, it was the blue MB stuff that did the trick ! Anyway, the leak on No. 4 was not due to corrosion - rather a small bit of the gasket had ' burned ' and caused the water to leak into the oil at the oil return orifices right at the back of the head.
With Chris' "Wilhelm", the valve grind and decoke was part of the sale and maintenance arrangement. It had not given any trouble. As a matter of interest, there are plenty of pics for both jobs in another section of the forum. Regards Styria
