jaycoop, Is this the
Olson's in Washington state vendor you are suggesting??? I checked for contact info for "Gasket City in Ontario, CAN" and found
this Contact Us page. Is that the correct info??? The "Gasket City" web page info doesn't seem to have been updated in a long time.
When I was working on the 503 that broke down on Ed Pruss in middle Tennessee a few years ago, I got the last head gasket set that Gasket City had in stock. They also had a single head gasket, which I didn't choose to buy. I ended up doing a temporary fix on a leaky head gasket with water glass (Sodium Silicate) to get the rig to Kansas City, where Ed picked it up and drove it on to Denver. I believe he used the gasket set when he did a more thorough fix after getting the truck home. That happened a year or two pre-Covid.
Jerry