I got a 2nd hand head from ebay germany. It seems OK, came with valves, which were all OK in their guides. I transferred the cam and rockers last weekend, and the head is waiting to go on, prob in 2 weeks time (I'm studying away from home, so this is awkward for me).
Hopefully will be back on the road by Dec 1st.
The head was not as expensive as I thought, I got it for 181 EURO incl delivery from Germany to Ireland.

I was thinking on its failure, I put it down to using crap coolant, and gradual weakening of the crap coolant by topping up with water. Didn't seem serious at the time, but this all took place over 4 years, i guess the strength was well diluted. This time. I'm going for a pre-mixed Daimler Benz approved coolant.

Will keep you posted.
G