Hi,
I'm quite familiar with the old AS212 arm.* Most of the above is total nonsense.
Its a relatively medium mass aluminium piped S-shaped tone arm. Ideally
what you want from a headshell is two locating pins, but try finding them.
I think your wasting your time worrying about headshells and arms.
If you really care convert the arm properly to a fixed headshell type . **
Technics made the best low mass headshells (which is what you want)
but its hard to discern the real McCoy from likely inferior chinese clones :
https://www.amazon.com/gp/offer-listing/B003DY5Q4K/ref=dp_olp_new?ie=UTF8&condition=new
rgds, sreten.
* I used one (original headshell) on the first turntable I rebuilt.
I didn't rebuild the arm, I did on the next to some benefit.
** Try using loctite instead of the rubber washer. Another trick to
try is a thin copper washer bent to be concave / convex instead.
It only works once generally, I think Kab sell them.