You will have to find/buy a better condition one from someone who has a spare parts playfield or just remove the rebound rubber and ball gate from yours, sand it to bare metal, prime and repaint or powder coat. Numerous Bally 70's games used this metal apron configuration so it wouldn't have to come from a Wizard.

You could try posting here-

https://pinside.com/pinball/forum/topic/the-em-seeking-parts-thread

I have a Wizard in the back of my van right now that I'll be parting out sometime in the next week or two. When I get a chance I'll see what the upper arch looks like on that for you.

That looks pretty salvageable to me. Why not just strip the paint, wire brush the rust off and repaint with an enamel?