Number of things to check and recheck.
Tire balance - done.
Tires round -
wheels straight (not bent) -
Tie rod/track bar ends -
front ds joint/yoke tight -
wheels lugs tight evenly -
suspension links tight -
tires proper air pressure -
steering stabilizer disconnect/connect - any difference
play in steering wheel/shaft/box -
I've got the same problem but my mph is in a much higher. I didn't run a steering stabilizer, but now do. Still have front wobble, but now it's just the wiggling of the steering wheel. Everything on mine checked out. Only thing I could and still think is the LTBs have such a large lug pattern that going around town in the 20's, the outer face of the lugs would grip the concrete and push/pull. Then as the tire rotates faster, the shifting between the front tires provided the wobble. I'm now running low 30s and probably will go a little higher next road trip for testing purposes. I also think I've got some play on the steering box.
Have someone just wiggle the steering wheel while you check out the tie rods, track bar, etc. Remove the front ds (tie it up out of the way) and see if that provides some idea to the problem. Then have someone else drive your Jeep while you get in front and look for the beginning of the wobble and where its possibly coming from.