I traded some shocks for a blue tinted one that was badly crazed (mine was bronze). Initially I just wanted it for the core value with the intent of having it refinished by Melrose. Like you I decided to take a shot at re-finishing it because I wanted to try the blue one in lieu of the bronze to see which I preferred.
It's not the plastic but the surface hard coat that has problems. You can't polish the hard coat, it always looks patchy. I started by sanding it off with 220 until I got down to the plastic below, then finer and finer grits to 1500. It takes awhile and I masked the edges so as not to damage them. At that point I power buffed it out and it didn't look too bad at all but it's never as shiny as the hard coated ones. You'd have to know to see the difference though. It took all weekend to do it and after, you have to take care when cleaning because it is relatively soft but I did use it for over a year and cleaned it with Plastix cream.
I never did use it for exchange and now it's my winter top since I've got two others, one of which has been re-done by Melrose. RE & re's come with new rubber mouldings, themselves worth $100 so you should take that into account if yours are weather beaten. I didn't find I liked one color over the other particularly and I would grab them interchangeably.
I did find out that all mouldings are not made the same. You will find the OEM ones have nylon fittings inside where the screws hold them. You can feel them when it's off. Most aftermarket ones do not and therefore don't work as well. I put new ones on the blue top to improve the overall look. It didn't need painting but that's another step. Good luck
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