A friend of mine has an early seventies Black Label 2002, 20" ride. I have a red label late seventies 2002, 20" ride. I can't tell the diff between his cymbal and mine. I have played his many times over the years.
I almost can't believe the consistency between these two cymbals. Its almost as if they were clones!
All of my 70s 2002s are thinner/lighter in weight. If you A/B'd my old '77 ride with a new one, you'd immediately hear a difference! My old one is lighter and washier than the new ones. Also my SE hats are from '74 - these old hats sound smoother and not as metallic as my Red Label hats... the bottom cymbal is a little different (more "scallops").
I never weighed my 2002s, but on some forums, guys have weighed their Black Label vs. Red Label cymbals and have concluded that the older Paistes were in fact lighter in weight (sometimes marginally, sometimes not).