Some questions on the 273 head gasket "thing".

Valman said
Hey mate, have a look at the Cometic Australia page here, CHRYSLER 318/340/360 V8

They have multi layer steel head gaskets with the smaller bore for the 273. Various thicknesses as well, down to 0.027’’. Might be worth giving them a call.

Much appreciated. I’ll have a look.
Those summit ones are a good price, but postage is a killer.