Alright! Great success. The Altima/Z/etc. bolt, 55226-JA01C, is perfect.
The bolts are absolutely identical except: the newer bolt is 10mm longer in the threaded part; and the anti-corrosion coating is that matte grey stuff you see on newer parts (hot dip?) and not the zinc+chromate plating of the original part.
The old bolt pictured is the nicest of the four from my car. It thankfully only took a little working back and forth with a breaker bar to break them loose, but at least two of them had the groove for the eccentric washer rusted/worn smooth, and the nuts and threads were in really bad shape in general on both of the toe bolts.
The -JA01C bolt should also work for cars that use 55226-0P000, which is the toe link bolt for the S14 (and I think S15, R33). The overall length of -JA01C looks to be the same as -0P000 but it has more threads and less shank. Should still work fine.