The shorter bb spindles tend to be more symmetric, and I've never seen a spindle shorter than 112mm that wasn't.

Certainly any Shimano cartridge bb shorter than 118 or so should be symmetric, so if you need the tiny bit of offset that the original bb may have had, a 1mm spacer can always be used under the cartridge bb's fixed cup to achieve a bit of offset.

I have here a (March 1985 made) vintage, 113mm Shimano spindle, marked as "D-3H" size designation and also "68=W=113" and "CrMo".

It measures perfectly symmetrical:

30mm from corner of cone shoulder to end of spindle (both ends).

10mm from center of bearing track to radiused start of taper (both ends).

I'd have been very surprised if the same-vintage Dura-Ace spindle was any less symmetrical than this lesser model, since the trend at this time was toward all tapered spindles becoming symmetrical (triples excepted).
But I also find an (October 1984 made) BB-7400 Italian spindle here, marked "70---W" that is 1mm longer on the drive side than the non-drive side, measured as above.
<<<This I would describe as only .5mm offset, since the right crankarm only moves .5mm to the right as the left crankarm is also moved .5mm to the right, thus making the right end of the spindle effectively 1mm longer than the left end of the spindle (yet another measurement-standard quandary?) >>>.