There has been some DIY work on the ports, so I wouldn't put **** headwork out of the question.
Took the top off one and it's running a single gasket up the top (were they multi layer originally by chance??)
The gouge in the port isn't high enough to affect compression apparently either. So my friend/acquaintance (from my previous 2stroke addictions
) is going to sort the head out to stop it contacting (machinist by trade) lap the gasket surface flat and get it in a state to be used. I trust him well and he is pretty onto it preparing 125GP and RS250 machines on a regular basis, so he can make my bunch of bones ring a ding ding once more!