Well, for some X there's always a base-2^X encoding you could use. If you can find 512 swears, you could do base-512. You don't actually have to do a base-2^X encoding, but that's more convenient as it means you're encoding X bits with each "digit".

But yeah, I'm not sure there are that many recognisable swear words in English. Unless you count massive compounds, but now all your words are really long, so you haven't gained anything.