Me, I have deep, DEEP scratches (seriously obvious, but not so deep you can feel them with a fingernail) on the '70 VW we're restoring. I've tried the Zaino Glass Polish with a PC. No effect. Ditto for 0000 steel wool and Bon Ami.
As I said before, take a look at other threads on this topic. Sometimes, you may need to decide to take the "I have nothing more to lose" approach -- which is where I am with the Ghia, but you may not be.
And good luck!