[Ginola]

Need to work out which one it is too yet!

For the costs involved I would just throw another engine in, It is not advisable to simply replace a head gasket anyway, nearly everyone recommends rebuilding the bottom end at the same time, for some reason replacing just the head gasket seems to lead to bottom end failure just around the corner afterwards.

I would look to source a complete long engine from one of the reputable breakers and then by a new timing belt kit/oil/filter/coolant and plugs and get someone to swap it in for you.