I'm needing the same thing, but for a '72. P.O. didn't install fronts. I measured mine with a forklift, came to 13 compressed and 21 ext, roughly. Trouble is, no parts stores are able to help with what I need, and I'm confused by the mount codes when shopping online. Did you get anywehre on your search?
As long as you have your compressed and extended length, call up your favorite shock manufacturer and tell them your numbers. They can tell you which shock you need. Bilsteins website used to have their shock dimensions, but I don't know if they still do. Personally, I wouldn't trust the desk jockey at an auto parts store.
Thanks y'all. I actually just went with 5113s today. They come up at the Rancho site, but for a 2-3" lift. Should work ok for now, and since the rears are already the same Rancho suggests (5118) for a 3" lift, I'll redo all four at once properly in the future.
Parts jockeys were no help even with my measurements, but enough time on the web provided me what I need!