There is an issue finding the correct 273 head gaskets. The gaskets that are currently available fit the larger bore 318, 340, and 360 engines. They are also much thicker than the original steel shim head gaskets. Add all this up and you will find quite a decrease in compression ratio. Will they work? Yep. Will you have optimum performance? Nope.
It took me six months to find a pair of original steel shim head gaskets for my '65. It was the last pair the guy had. Cost me a bunch. Guess he knew what he had.