Where to get 273 Head Gaskets?

It will work fine. It just might loose a bit of compression. I took 4" gaskets off my engine and didn't have any carbon build up in the void between the bore and
the fire ring of the head gasket. (Had a lot on the pistons though) Two previous owners ago, my Dart was owned by a old man that mowed lawns and hauled his rider around his small town in a trailer. All the hot rodding I did wouldn't blow the "cobs" out. LOL I hope the 273/318 gasket sets have the correct smaller port intake and exhaust gaskets in the set. Mike