Here is the lug Sonor used from 56-65 it is similar to the one from 65-on. it`s slimmer and less bulky than the sharktooth, and has no incert, instead it has a "throat". The studs are into the cast as well. The throat on this one is thicker than that of the 60`s and is not as pointy. easily mistaken between the two !! The 50`s one is the one on top in the first photo and the bottom in the second photo !! Note the thickness difference in the first photo !! You don`t need this one so look carefully !!
Just to correct you here: these lugs do indeed have inserts. I know that for a fact since I have a ca 1960 teardrop kit, which I disassembled into minutest detail.
Also, I doubt these lugs were used for as long a period as you describe. This isn't of much importance, but my impression is that they were in use for only a few years around 1960.
Finally, this page on the ST-Drums website will prove very useful to FatherTime: http://www.stdrums.de/tips/teardroplug/teardroplug.htm
This one may be helpful as well: http://www.stdrums.de/tips/renovierung/renovierung.htm
/Magnus