I wasn't clear sorry, this is the o ring around the stud/oil passage. not the cylinder sleeve o ring, but thanks Mike, that one hadn't occured to me at all.
I took a tall stud/ head seal for a newer engine, slipped it over a socket, then found a sharp razor blade and a piece of aluminum .125" thick. I laid the aluminum on a flat surface and put the razor blade on it with the sharp edge hanging over. Then I rotated the socket and seal against the blade with a little silicone for lube. I sliced off the appropriate height seal to replace the too thin O ring. From the bottom of the groove to the top of the two base gaskets measures .110" I cut two seals .130 for some crush. I sanded them smooth and will set them in a small amount of hondabond in the groove. I'll get a picture if anyone wants to see.