Gotta have high temp O-rings, at least for the compression side.
I use Viton versus std. rubber.

Should be able to order thu local supplier. Have a machine shop cut the grooves for you.. Not much to it really.

I've got a cool head now, with the O-rings... works great! No leaks, no thick gasket.

If you can't find any.. I'd be willing to bet many motor builders could hook you up... Someone mentioned Trinity also does custom work on the stock head for O-rings.
(Not that I would trust Trinity)