Back when the topic of Chevy 305 head gaskets was covered three years ago on this forum the options if you don't want to have your block decked (so you can use the readily available thicker composite 305 gaskets) were to use the Fel Pro .015" steel shim gasket for the 350 bore or to reuse your original gaskets sprayed with copper gasket sealant and hope for the best. Is this still the case? Wouldn't the .015" gasket increase your compression ratio since it's thinner than the original, which I believe was something like .020-.021"? Mr. Gasket makes 350 bore shim gaskets in .018" and .020" thicknesses, which would be closer to the original thickness, but in their catalog they say not to use them on a 305 for some reason.