ONE other thing to consider in the non-return-to-center issue is the steering gear adjustment. IF it is adjusted too tightly, you'll have to manually (even with power steering) the steering wheel to center after every turn. Too loose, slack on center.
On my '70 DH43, the "slack" is on the input side of the gear, not IN the gear itself. The input side of the gear will move in and out before the inner part of the gear starts to move the wheels side to side. But it still feels the same and the most obvious adjustment location is on the top-side of the gear. So, you might start loosening that adjustment stud about 1/8 turn looser, then lock it back down with the nut, and see if that might help things or cause more issues.
IF somebody earlier had tried to remove any on-center slack by adjusting the upper adjustment, THAT could be the issue. An easy fix with a wrench and such.
Not to be critical, but those alignment results don't look too good to me. Unless the roads you might be driving on are cambered more than normal. BUT it does look better than when they started! Pretty much everything from '65-'73 should have the same or similar alignment settings.
IF you have any wheel spacers and/or a more outboard backspacing on the wheels (like less than 4.00" on the wheels), then the adjustments can become a bit more tedious to get to the specs. In theory, the farther out the wheels are from where the adjustments are, the more precise the adjustments will need to be, due to that greater lever arm (of sorts).
Be sure to ALSO look at the coupler on the gearbox, too, for a possible location of undesired movement that somebody might have sought to get rid of with the steering gear adjustment.
Just some thoughts, observations, and experiences,