Fastest and easiest solution is to swap rear handles.
As I wrote before -- there are four rear sight shelf heights. Here's a comparison of what I think you have (on the left) and a GI handle on the right (note where the bottom of the windage drum sits in relation to the elevation knob):
http://i884.photobucket.com/albums/a...15/CHcom-1.jpg
Alternatively (and a lot of work) would be to bring up the front sight. Drive out the rear sight pin, remove the sight, place an appropriate shim or washer around the sight column (so the base sits on it), and replace the pin. Crank to lowest setting and re-zero. Done.