Thanks for the measuring photos. I can see why you are having trouble. This is a tough call. It took me some time to get good at measuring stamp heights to the accuracy needed to tell a 1 3/16" from a 1 1/4" especially if there are any parts which aren't pressed in well. In the process of learning I discovered that Bill Hartrick's original measurements don't seem to be exact, which doesn't help. Like you I was using vernier calipers and I kept getting measurements which weren't quite right. So when Bill says 1 3/16" it isn't accurate to 0.001" or anything like that. I think that he was using a tape graduated in 1/16" and he gave the "closest" 1/16".
Perhaps Bill (Drumaholic) could comment on this? What level of accuracy was there in your original published heights? ± 1/16" ? ±1/32" ? ±1/64" ? And how accurate would you think measurements need to be to reliably identify two stamps which only differ in height? I believe it's 1/16" but I'm guessing about your methods of measurement after the fact.
Also, coming from a metric country myself I found that measuring accurately in metric system then converting back to fraction inches was often confusing. Maybe I should add all of this info to my "how to measure a stamp" section, but I didn't want to scare people with even more detail.
Based on the bold ZILDJIAN compared to the AVEDIS, and the vertical alignment, those all look like 50s and 60s stamps. I don't see anything 70s in there.
The 20": this has the three dots and I'd say it is closer to 1 3/16" (which we would like it to be) than 1 1/4". I say that because it looks like the jaws of your calipers are just at bit wide. I can see plain cymbal below the MADE IN U.S.A. and since it only takes 1/16" to make the difference I'd say it is a 60s stamp.
The 18" kh: this doesn't have the three dots. The stamp is well pressed in, so I'm thinking that it must be a late 50s small stamp. There is another test for 50s versus 70s which we can apply, but I'll come back to that.
The 14" hat bottom: the measuring pic is hard to see, so I've gone back to your earlier post. I've seeing a late 50s small stamp once again. It has the bold ZILDJIAN and the vertical alignment. It is possible that the top and bottom hat are from different stamp eras (no big deal, sometimes they came to the retailer that way from the factory). I think you have only shown us the bottom stamp so far.
The 18": this also doesn't have the three dots and does look like a late 50s stamp.
I think what Mike was thinking is that one of the three dot stamps could possibly be a 1954 stamp. Although this is unlikely it seemed a good idea to rule it out. The thing to look for there is whether it has obvious hammering on both the top and the bottom. That's the giveaway, because in the mid 1950s they were still doing lots of hammering on both sides which tended to stay visible in the finished cymbal. Which brings me to the other thing to check out to tell a 50s from a 70s cymbal. Some time during the 1960s the hammering seemed to be done only on the top. At least, it only appears on the top in the finished cymbal. So, for example, if that 18" kh looks absolutely smooth on the bottom (no hammering visible at all) then that is more of a 1970s style. The visible hammering on the top also has a more systematic look to it in the 1970s than the 1950s. Again that is a product of changing production techniques. I'm still working on collecting up examples and writing up a specific section on hammering. You can see some hammering shown in the gallery, and it is also worth looking at the 1960s hammering example in the New Beat section:
http://black.net.nz/avedis/new-beats.html#Top-gen1-ham
This is your typical more systematic hammering done just on the top. Nothing obvious on the bottom side:
http://black.net.nz/avedis/new-beats.html#Bot-gen1-ham
Notice that your hi hats won't be "New Beats" proper since they came in later (1963-ish). But they do seem very nice weights. In fact, as Mike said all those cymbals are nice weights and should you should have a really nice sounding set. And they should go well with the Jazzette you just scored.
Please excuse me for overloading you with too much information. You should really just enjoy them rather than getting too detailed about the dating.