I'll bet quite a bit of money it's not a direct bolt on change.
You'll have to pull the entire chaincase.
The 05 900 chassis a keyed shaft or spline shaft? The quick drive pulleys go on a splined shaft.
The center to center between the shafts probably isn't the same. The belt problem won't be the right length.
I would consider using a Kurts Pro geardown as a starting point on a project like that, since you can get the belt for them in different lengths I believe, being a more standard tooth design... would probably have to machine down your chaincase to open it up, not sure... maybe TKI already has a kit for the 07 and newer Dragons but again C to C is different on the 900.