The Battlezone control panel does not use an overlay. The graphics are painted directly onto the panel. So any "Battlezone" overlays you see on ebay are incorrect.
If you are just planning on this being a general Mame cabinet, then forget about both the Battlezone sticks and the periscope assembly. Try and find the face assembly to a non-periscope Battlezone instead (not too hard to find, a Red Baron one will fit too).
From what I saw on ebay it looks like the guy gave up on a Battlezone project. He might very well have the control panel and other missing parts available to purchase.
Also, if you are truly going to do it original style, then you will need a half silvered mirror and a set of backdrop artwork. The monitor in a Battlezone mounts inside the cabinet facing straight up, and then is viewed on a mirror. You might have trouble mounting one for direct view (I don't think there is enough room in there to mount one for direct viewing).
If you don't want to spring for the (often expensive) half silvered mirror and backdrop artwork, then just go with a normal mirror. I can measure mine so you can get one cut if you want.