When you were taking all of the pains to get things square, did you do the "diagonal" measurements from standardized measuring points, or just front to rear?
As for the stub frame and the one wheel being farther back than the other one. THAT should have been visibly evident as the wheel would not be centered in the wheel well, I suspect. It should not have gotten out of the factory like that, even back then.
On a single-pivot lower control arm, not much f/'r movement is allowed. What's there is basically for impact harshness absorption, not major movement. The strut rod is there to limit such f/r movement, which is what the bushings help with.
If one of the existing strut rods is a different length than the other one, then "something" made "on the road" made it that way, not Chrysler. Also check the front of the stub where the bushings mount, for flatness. Reason I say that is that I happened into a '68 Buick LeSabre some time back. That year has the GM strut rod front end, rather than the normal lower control arms. The lh side obviously saw "something", as the strut bushing surface on the front crossmember is concave rather than flat/convex. The strut rod was cut in the middle, then re-welded with rebar as reinforcement, to compensate for that difference in resulting shorter-needed length. Good alignment and driving characteristics, especially with the Delco gas shocks I put on it later.
So, my respectful orientation is that the stub frame got tweaked by "impact", rather than being sloppily assembled at the factory. Did you check the diaonals on the stub, too? (Diagonal dimensions are in the FSM.) Just curious.
In my way of thinking, it's not the strut rods' job to pull the lower control arm forward or push it rearward, to center the wheel in the wheel well, that should be a function of the lca mounting in the stub itself. The strut rods should just locate what's already there, f/r, in a neutral manner on the lca pivot bushing. IF you're trying to compensate for a different dimension from the lower ball joint forward, with the lca mounting where it's supposed to be, it could well affect the particular wheel's caster as the body moves up and down, which might "steer" it a bit in the process, leading to the side with the most caster.
Just some respectful thoughts,
CBODY67
I have seen a nationally-ranked Skylark GS that has the front wheels visibly not centered in the front wheel well. VERY visible, but it's a full OEM-correct restoration. Made me wonder how it came out that was after a full restoration (when anything of that nature should have been corrected).
Just some respectful thoughts,
CBOdY67