I just did the exact same thing as you. I put '83 widetrack axles in my '77 cj5. You must use the widetrack steering linkage.
The only other issue is the front shocks. The axle has the mounting ears for the shocks, so you can either use those or use the spring plates. I used the axle mounts because it will allow me to run longer shocks. If you do this you must also use the tall shock towers. I cut my factory shock mounts off the frame and bought a set of used tall shock towers. I had to order my lift kit for a widetrack cj7 so I would get the right shocks.
Good luck. Let me know if you run into any problems.
i did a similar swap as well. on the front end, i cut off the axle shock mounts and used the spring plate mounts. i have a shackle reversal and the axle was hitting the shocks so i also moved the upper short mount back about eight inches on the frame. the rear i used was out of a 70 wagoneer with a 5 on 5 1/2 bolt pattern. it's only a couple inches wider than the front and only noticable with a tape measure.