Since I am 6'5", I can relate to the back ache problem caused by the low bars. Essentially, I tried every bend on the market, and nothing was high enough. As a result, I went a different direction. I had a Pro Taper tripple clamp from a CR80, and noticed that the bar mounts were 1 inch higher than any of the pro taper mounts I had for my KX. Since they CR80 mounts were bolted on, I removed, center drilled and taped a hole that was slighty offset from center, and installed on the KX with the offset forward. I then installed a set of High bend bars (not sure which bend, as I have a number of pro taper bars laying around, so I just grabbed the highest bend). The difference is amazing. With the extra inch, I can now stand straight legged, hang over the front fender, without bending at the waist excessively.
Another solution I have noticed after my modification is to simply install an aluminum spacer under the existing bar mounts. You must use the bar mounts that affix with a bolt coming from the bottom of the tripple clamp upward, and simply install a hardened, longer bolt through the rubber mounts.
As a note, I was a little concerned about the extra height causing a weak point, but have not had any problem, even with a few rough crashes.
Good luck.
Rick
