Alignment of the steering linkage itself could also be a factor. I have found numerous Mopars over the years that had shims behind the steering box where it bolts to the K. You can alter the plane the linkage operates in by shimming the box to move this plane up or down. There also is the possibility of idler arm and its bushings not duplicating factory position, or the bushing is worn/bad and allow unwanted motion, or its specific mounting location is just slightly off. Or, in the case of ultimate tolerance stack up, a little bit of everything above is off, just a hair, but add them all together and now something hits.
Personally, I'd much rather install a 1/4" shim into an motor mount or try moving some other pieces of the puzzle around to create the necessary clearance before I'd hammer on a $400 oil pan.
Don't shim or remove shims from steering box without checking bump steer, this will change things.
One of the gm suspension gurus used to reccommend limiting steering travel on road race f bodies.
He pointed out that for track use giving up a little travel was worth gaining oil pan, header, and tire/fender clearance.
I think he welded stops to the crossmember, might be a way to do this on your car.
