Surely you could have fixed what happened to yours mate. Could you get a grab onto it with a tack weld or easy out? worst case scenario would have been drilled out, alloy welded, and then retapped to install a helicoil. Did you take it to a cylinder head workshop? they might even be able to heat it up to help its removal. Just seems a shame with all the work you've already done to it (just seeing if you've explored all possible alternatives first).
I have a head with bent valves etc.. but useable! However i was going to sell it to someone who wants a fucked head.. (so they can do some manifold making off it) how bout you sell him your head and i sell u the head i was going to sell him