[Leica] Tripod head recommendations for a 560 lens

[abridge at gmail.com (Adam Bridge)]

I'm wondering what folks are recommending as a head for suppling a
560mm lens mounted on my Canon 1Ds Mk II.

I actually have a wonderful fluid-head tripod I use for video work
that's more than capable but it weighs a ton and it's mounting is a
bit awkward. I have a ball head but it is sized for use with the M8
and the 1Ds without a long lens.

Thoughts? Recommendations? Thank you!

Note: A shoulder stock is out of the question. I lost a lot of
mobility/strength in my shoulder when it was shattered in our car
accident a few years ago. It works but isn't strong enough to steady a
heavy lens.

Adam