Take a read at this thread - I-20 road condition East from DFW
. I don't know about I-40 east of Little Rock. The worst stretch we saw was US-67/167 northeast of Little Rock -- rhythmic oscillations from pavement sagging away from the seams -- an upside-down equivalent to old wooden ships getting hogbacked if you ask me. I-30 southwest of Little Rock has some of the same conditions -- it gets much better as you near Texas. We slowed down to 50 mph to make some progress but I still found some rivets popped inside after that trip. Right hand lanes sure get pounded by semi trucks and it is hard to cruise much in the center lane in this busy state.
We drove a couple hours on the east-to-west US-60 in southern Missouri -- a dream by comparison! That's north of your route and would need broader info from other readers. Post back here after your trip and let us know the good and bad of the route you used. That is