I'm not sure that the backglass is that bad. It is not completely faded, you would see gradients of fade across colours (like the building on the left). The fade (if it is fade) is completely uniform. I think the backglass was originally like this. The white areas around the score reels can be masked and painted. The "Stern" and "pinball" can be cut out and repainted. P "Player 1" etc - same deal. The front of the taxi looks like it has peeled off (hard to tell from pictures).

I would try to restore it - you could not make it any worse. There's a thread Mitch did on a Zaccaria "Universe" ;

http://aussiepinball.com/index.php?topic=1357.0

That would provide you with a guide on undertaking the resto.

You could try contacting www.bgresto.com - they might have one in the pipeworks.