Caseback looks correct for this vintage of polerouter/microrotor.
The glaring deficiency is the crown, and the crystal, which appears to be a poor replacement based on the tension ring.
Judging by the general cleanliness (or lack thereof) of the movement, case and caseback, I'd guess that this hasn't been serviced in a while. So be sure to add watchmaker and parts costs to your equation. If you could find a crown, I'd say $80-150, $25-50 mainspring, $10-25 crystal.
I'd have to see it in person to tell you more (like whether that dial began life on that watch).