Chances are, you may need successive grits, and it wont be perfect if you have deep scratches. The way to polish anything is to start with heavier grits to remove the deepest scratches, then work down to ultra-fine grit.
I have used Micro Gloss before for that, it helped some. Not totally. Its about 1 micron rating as a final polish, about as fine as it gets. I would need something more coarse probably to do better.
Perhaps a headlight polish, followed by something finer like micro gloss.
Whitening toothpaste also has mild abrasive. Test on small area first.