Very little overhang behind the pivot point, so a counterweight would have to be massive to have any positive effect. Lack of mechanical advantage.
Also not much height available for the usual spring approach.
I'm thinking a hovercraft approach would be good.
The pivot mechanism and cartridge mounting bits are both wood, and do have an OEM look to them. Haven't done any research on this at all, though.
Cartridge seems to accept Victrola-style individual needles, with a set-screw arrangement.
I'll update this post with pics in a little while.
Here we go:
Pivot mechanism
Underneath head.
Needs wire throughout, but suspension is still pliable and flocking is 'arite' for now.