If the dropout width (separation) is 120mm or so, which is the intended width, then BOTH stays are bent to the right. You'd want to move both to the left by half the right/left difference to establish symmetry.

BTW - it's common for both stays to bend together like this pair did. Figure a bike hit by a car with the wheel bolted in. The rear triangle is bent sideways, but the width is constrained by the wheel's axle leading to what you see now.

You have an opportunity here. Consider bending only the left stay to the left by 9mm. That would give you 130mm axle width for a more modern wheel, and close symmetry. Of course it would be serendipity if it worked out exactly, so a bit of fine tuning, or calculating (or both) will be called for.