The years of the hollow logo are very questionable. Francis says 1978, however I bought a ROCK 21 with the HL in 1976! I wiped the logo off a few years later. Can't prove it but I know what I bought and when (from Manny's). I still have it and it's a 70's stamp. That's the only Zildjian I bought...
I think I can see the first top dot (above the 2 that should be there). The lathing is quite deep in that around. I also seem to see the H/E. But of course, I might be wrong. Not the first time in my life. :)
Now that mlayton concurs, here is the key to 60s vs 70s. I wasn't 100% sure from the pictures so wanted someone to agree.
60s: H over E - turkisH madE
70s: H and E don't line up.
As you could see the first one was 60s, but the second was tricky. That stamp isn't as impressed on Made, so harder...
Sadly, your set does not seem to pass muster with what you have. I'd say that's a medium lathing tool on all three. The mystery bell in question uses a finer tool.
However.... What you MAY have is a standard Zyn (not Super or 5 star).
The bell you do have:
Somewhat fine lathing.
Black Label, could you show us a picture of the Zyn you have? The bell lathing style will show if it matches (or close).
Edit: I looked for Zyn bell pictures and you may actually have an English there. (Zyn with no stamp, maybe a second.)
The bell we see here is a little different than a usual...