My situation is the opposite of yours in that I carry most of my height in my torso. But last summer I went to a bike shop in Vancouver BC and the guy made a few quick measurements and told me the frame dimensions I needed. Honestly, I really didn't trust the numbers. When I returned home, I had two different full-on 'size cycle' sessions at two different places and all 3 sets of numbers were within a few mm of each other. So that guy in Canada was spot on.

I searched the web looking for the method he used and think I found it at:

http://www.kvanproductions.com/cycling/frame_sizing.htm

I've since used this to size 3 friends and all are really happy with the results.

Maybe this will help in finding the right frame for you....it's definitely more than just a standover height issue.

Jim