I remember a thread on it yrs ago but seem to find it?
It's not just on the K0, but all of the 750s (and other SOHC4 engines).
The head gaskets today are thicker than the old ones because of the switch to not using asbestos during the 1990s era. Today they are 1.0mm thick where they used to be 0.8mm thick.
If you're rebuilding one of these, PM me for some of the extra-thick O-rings: they go into the 2 oil passages at the back of the cylinders, in the big holes in the head gasket there.