There is a company in MN , Roxspeed,
http://www.roxspeedfx.com/ that sells a lot of different risers, some vibration damping, that will work fine on the Enfield, with its "unconventional" clamping arrangement.
I put a set on mine, and they work well. Of course, if you go too far up and back, cable issues can come into play, as they can with any bar change. Also, if you get Roxpeed's stuff, notice that some of them change from 7/8 to 1 inch, so make sure you get the 7/8 to 7/8 risers, so they work with the RE's bars.
You might be able to see these on the pics of my bike and hack.