This is a well documented retro fit. The eye to eye length is not a problem – there are plenty of shocks with 222mm eye to eye. The problem is the stroke, which at 2.5 is a little unusual. The way you solve this is by blocking off the last .25″ of stroke on a 2.75″ model, using a large plastic washer between the spring and the retention collar. You can either do this yourself or you can get mojo to supply you one with the washer installed.
The issue of the valve cap on Fox DHX coil damper fowling was mostly constrained to older (3 years plus I think) versions of that damper where the valve cap stood proud of the piggy back.
You could also get a Cane Creek to fit as they are all made to measure anyway.