Sorry I can't offer any comparison photos, but I have three J-8s that I have shot with (I've got a fourth somewhere that I haven't used).
I have a 60s LSM silver-coloured one (which came with a Zorki 3M), and an 80s LSM black anodised one (which, I think, came with a Zorki 4K). They are really very similar in performance, and both very good.
But the best I have is probably (I've only shot one roll of film with it, so I can't be sure) a silver-coloured one in Kiev mount, from 1975, that came with a Kiev 4. It seems to have a definite edge in sharpness and contrast compared to the other two.
I've heard that different eras produced different percentages of good lenses, and it's certainly believable that the 80s was one of the most variable periods for Soviet quality control (I've seen Zenith bodies from that period that looked like they were assembled using nothing but a hammer). But, I really don't think there's any way to categorically state that lenses from one era are better than lenses from another, because the range of QC was so wide that every era produced everything from dogs to gems.