I would presume it to repairable, but the best answer would be from Langcourt or the like. I would give them a call and worst case is you are out the cost of shipping with a good and reliable response.
May I ask what year, displacement, and how many hours, if known? Any symptoms or was this a discovery during service?
I would say not personally. The crack looks like it started at the exhaust port and spread upwards, meaning there's a fair chance it's cracked down the exhaust port too. To be honest, it'll make a great paper weight, just bid assuming that your just buying a head, and hope you get it cheap enough.
No mate, I was talking to the guy that's selling it. I was going to bid because I wanted a spare head to modify, but bought one elsewhere. You can buy a bare cylinder for about ?270, by the time you've bought that one, had it welded and replated (including vat and postage), it'll probably owe you ?200+. For me that isn't enough of a saving to bother with.