I'm not sure if the lighter J series would adequately support a Deardorff 8x10...and the A series of tripods with the double tilt head is much heavier than the J...the A series in its case is not easy to carry for a long while, especially over the shoulder. Of course, you younger guys do everything easier.....:}
'dorffs are surely the heaviest 8x10s out there. I don't think I'd want to try using them with a J series, especially if your lens is at all heavy. Ries recommends a maximum of 16 lbs. for the J series.