I can't place it. But, with the embossed 'brake wear' marking, makes me think late '60s - early '70s.
It's mounted backwards, that particular brake backing plate should be on the left side.
If kept on the right side, and if the brake cam is non-symetrical, it would need to be rotated 180° to prevent trailing shoe gouging.
And, the brake stay is dangerously close to being a straight line between axle and stay mount bolt.
The brake stay endpoints, and the axle center, should form close to a 90° angle.
Rocker plates normally fit outside of the fork legs. Is that a special setup?