That's why sewing your own pants or getting someone to sew them for you might be better. The idea is to fit the pattern to your body so the rise is the proper length and the pockets are in the right place.

You could always try taking in the crotch seam--I'm not sure if that will work because I've never tried it, but talk to a tailor or seamstress and find out.

Better yet, check out the REI Sahara pants that Heber and Leadfoot suggested. I tried the women's version a couple of years ago and the rise was way too low for me. If the men's rise is also too short, it might be just right for you.

I'm not really sold on convertible pants. I wore some on a couple of trips last summer that featured river fords, but found that the nylon fabric dried so fast that it wasn't worth the bother to zip off the legs--especially when the lower legs were muddy and needed a wash anyway! I'm not sure they're worth the extra weight. However, I don't wear shorts--varicose veins and knee surgery scars make my legs pretty horrible to look at, and I'm allergic to most sunscreens so have to keep covered up anyway. I also don't use the pockets, because they interfere with my pack hipbelt. But YMMV.