The J heads were cc'd to 67cc's and had a mild porting job. The X heads are untouched, as-removed with a whole lotta miles on them. I have not measured the X heads.
I would CC the heads. That's the only way to get a guaranteed answer. Besides, if you're going to do any work to them, you will then have to mill the head to bring the compression back up anyways. So you'll want to CC them anyways.