The lathing on your hats is what I'm used to seeing on cymbals from the later half of the 1950s. Multiple passes seem to be done, and with at least two different styles. There is a fine pass (small tonal groove) and a coarse pass (larger tonal groove). Your hats also show some oven crust left behind (photos 4 and 5) which happens when the lathing is not deep enough to remove all the crust. The bell also shows some lathe chatter which is another thing which is more common in the 1950s than the 1960s. Most late 1950s cymbals have fine tonal groove lathing on the top side of the bell, although this isn't matched on the bottom side of the bell. You can see the variation in bell treatment here:
http://black.net.nz/avedis/bells.html
It will be easier if I do a little annotation on your photos to show what I mean. You might need to refresh your browser to get the annotated images to appear in my previous post.
The change which happened in the 1960s is coarse tonal groove lathing over the whole bell, and less obvious differences between coarse and fine tonal groove lathing across the bot (both top and bottom). Notice this is a change in the frequency with which different lathing styles are found. It is still possible to find a cymbal which has coarse tonal groove lathing on the bell, and a late 1950s trademark stamp. Similarly it is possible to find a cymbal which has fine tonal groove lathing on the bell or bow, and has a 1960s trademark stamp. By the 1970s the lathing has changed again with larger tonal grooves which are more consistent than the 1960s. Again this is a frequency change and one can find counterexamples.
I'm not sure if this addresses your observation
Also kind of wondering why the lathing is so dang sharp and deep, way more so than my 60s/70s NBs. Is that just a thing in the 50s?
and maybe it would be a good idea to see both of your New Beat hats as well.