Thanks Mark.
I have that manual,
It tells me the bore is roughly 77mm and I can work out the thickness from the ring grove - the side play
However the radial depth is a problem.
The engine is in a mower that is used every day by an elderly gentleman basically as a wheel chair.
I did try to get him to use one of my loan out mowers but it just did not work out, he got confused drove through the rose garden & cut himself up quite bad for a 94 year old.
So I was hoping to assemble all the bits before I tear down or at least make sure I have the bits before I tear it down to keep the tear down time as short as possible.
Not being a Kohler agent I have to go through a retail outlet and they sting me $ 135 each side with no returns on rings.
Add to that the " Kohler rings" box has rings that mike up as being imperial and others with the same bore that mike up metric with the major diference being the radial depth.