Been working on changing out the handle bars with 6" risers an figuring out what to do with speedometer from original clamp mount. So far what it looks like. Used a fabbed clamp to risers an a 02 sportster speedometer case.

 

Looks great. There should be a lot of guys interested in what you have done as a lot of owners are unhappy with the speedo and/or buckhorns.

 

You may want to look at the Accutronix speedo adapter that works with the risers similar to what you already have. You may want to look at the Sportster Custom 2003 and older setup that mounts the speedo under the handlebar clamp. I used the 2004 and up clamp arrangement to mount mine (look up some of my posts) but it has integrated risers so you would be locked into that riser setup even if you found you were not happy with it. The older setup I mentioned looks like it could be used with any riser. A long as the tank is not raised there should be no clearance issues.