Some questions on the 273 head gasket "thing".

Just getting ready to post on this very subject with compression ratios. Cometic gaskets are custom only for the 273 and not MLS. On 273 head gaskets there is a funky cutout to match the cutout on the block. If you do not have the cutout on your block you can use the 4.04 x .027 Cometic gaskets. Other than that a standard factory 318 head gasket is 4.01 x .039 and fits the head chamber nicely. Fel-Pro and Victor gaskets work well but the bore is larger. So yes, a decrease in compression.