Well, you could go air, but look for something with a good volume. I'm currently running an X-Fusion 02 PVA on my Jamis XLT and absolutely love it...way better than a Fox Float R (I weigh 230lbs BTW). But they're hard to find right now in the US.
One thing, I recently upgradedd my rear shock, and I had to order a seperate mounting kit for the Rock Shox I put on there. That was an additional $35 expense. If you stick with Fox Shocks you should be able to re-use the monting pieces already on the bike.
As far a mounting, I think its a 24.0 on one end and 22.2 on the other and 6mm mounting bolts.
Good info. I've got an 06 Dakar and it too is the 6.5 x 1.5 version with 22mm and 24mm w/ 6 mm bolts. I was thinking of going to the CC9 myself but want something for the road or hardpack and the ability to reach down, flip a lever and be ready for the suspension to do it's thing too. RP23 is nice but PUSH wants way too much and buying a used shock from someone doesn't interest me. So I save my lunch money and wait. Good luck and keep us posted.