I can't guarantee this is your problem, but the 1973-1974 140's used a different idler arm and you might have to use the later idler to match the later steering box and pitman arm.

I do know that the pitman arm on the 1973-1974 steering box is different and is not interchangeable to an earlier 140 steering box as the pitman shafts are different sizes, but the angles maybe different too.

I can tell you that whenever we update an early 122/1800 idler arm with all metal bushings to the later style idler arm with a metal cased rubber bushing, we have to change the pitman arm on the steering box to match the later idler arm which has a different angle. Fortunately, the pitman shafts are the same size, so they are interchangeable.
--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com