The only thing keeping me from showing my car is the rear window has etched in water spots and scratch/scuff marks I cannot clear. Has anyone had success with glass cleaner/polish that basically restores glass??

 

Water spots, maybe you can get them out. Scratches will never come out with like that Eastwood kit or cerium oxide. It's a huge waste of time to try to fix glass. Buy a good or new piece and replace it.

 

You should replace the glass. It's hard to find but these guys carry it. I had to replace my front glass as well but it was only a little more to get the whole package (side glass too) and now I have nice matching tinted windows. Good luck.

http://www.autocityclassic.com/

 

I polished the side and back glass on my 67 Nova SS using the products from Eastwood with varying degrees of success. The back glass had relatively heavy scratches form someone hitting it with a DA while sanding. I was able to remove the scratches, but did create an area that was warped in appearance. Not a great result...
On the other hand, the side glass was covered with fine scratches that were caused from years of winding past dirty fuzzies. These scratches cleaned up easily and saved me a fair amount of money.
Bottom line is if you can catch you finger nail in the scratch, chances are you won't be happy with the results of polishing.

 

My 67 442 had pretty deep white scratches on front glass from the wiper arm. I wanted to keep the original glass so I tried the polish kit. It took a really long time and effort but the white is gone with most of the scratch probably still there but it is acceptable to me and it is hard to notice it is there. I am happy with the result.