At this stage in the game (eight months and ready to give up) I'd accept the fact that l had done my best with it.
Take it in to a specialist (not the LR dealer who charge £125 per hour)
OK it might still cost you but it'll be running again.

Hi, there is a thread on the forum regarding differant types of head gaskit. This takes into account the travel height of the pistons. Plus what problem did you have before head rebuild.