I have brought back a few sets of 3rd gen Daytona headlights recently by doing this...
1000 grit with a 3M rubber squeegie and soapy water solution to get most of the inperfections and to get the yellowed factory "anti-scratch coating" off. I actually sanded off all the markings and letters to make it totally smooth.
Then,use 1500 grit with the squeegie and soapy water to get the 1000 scrathes out.
Then,use 2000 the same way to get the 1500 out
Then,use 2500 with soapy water by hand this time with no squeegie as a backing to finish the sanding.
Then,get yourself some 3M plastic polish and use a 3" 3M wool pad to buff out the scratches from the 2500(it will now be almost perfectly clear)
Then,finally use a 3" foam pad with the polish and if you did it right they should look NOS:thumb:
I brought back a set that you could hardly see out of to look new and took a pic of one done and one un-touched I will have to post it later.