Valve choices

Killer6 said
The avg piston is so far away from the top, that's not a problem, as long as the head gasket is big enough, same as other long-stroke engines. Unfortunately, it appears the large-bore Aussie gaskets have become difficult to obtain, so the limit is the current ACL @3.55"(-.020"). Printoseals being @3.53"(-.020"). Unlike SBC & BBM, Slanty valves are pretty well centered in the bores, less of an issue.

I don't know what all the hooplah is about the Aussie "big bore" gaskets. Almost every gasket I have here measures 3.55". I guess maybe if you bore one .100" then you might be concerned. I'd go to Cometic though, before the overpriced Aussie piece plus paying shipping from down under.