Points all noted Grumpy,
Love your post #62854, all those points where not at the forefront of my mind, they are now though.

I'm certainly not advising others to follow my lead, just thought I would share this repair with other forum readers. Plus I see the embodied energy in an item like this & like to try and save it, but it has to be economical for me to do it.


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The fella's in fitting couldn't find their internal micrometre, I'm going to have to get one of those.
With the ring gaps measured, I'm sure it will be fine. If I didn't have some level of confidence I wouldn't move forward.

This is an interesting engine design, very different from what I have seen before.

With assembly: The piston rings slide in by hand with a gentle push of a screw driver here and there. The cylinder having a taper lead in makes it easier.
The piston & con rod are marked well for its orientation.
Crank has an arrow and cylinder has a mark to align, cam has the 2 marks underneath to line up, then fit the belt.

Not sure about the sealant under the valve cover, I would like to see a cork gasket there, especially for a cover that comes on & off for periodic servicing.

I am chipping away at it, will let you know how it works out.

Happy is he who penetrates the mystery of things.