found some X heads

The X and J are the same head. The difference in flow numbers is nothing and the same difference's can be found from head to head of the same casting number/letter.

As shown, the Edel. heads flow like preped stock J or X heads or like a mild port work on lesser heads. This has been know and documented before that the Edel. heads flow like this. They do very well on the high end for as cast part. Preped well, before useage, they'll work best without a partial or full porting expense.