Probably best to find a dead F4 that has nice cosmetic parts to transfer over. Unfortunately, there really isn't a good way to restore the matte finish on the top covers and rubber grip parts... There is that eBay seller, procamerarepair, who has NOS F4 parts for sale. Might be another option, if you can't find a nice cosmetic donor.
F4s, F2AS, F FTn, FM2n, Nikomat FT2 - John Laughlin Photography - nature photographer
@ Kilted f3 nut Thanks for the advice. Seems a costly way to tidy up a camera! The marks are not that bad, but because it has no scratches or dings I wanted to just spruse it up a bit to look like new! I know there are automotive products available for cleaning and renovating rubber and plastic parts, but I don't fancy using them without some good advice! Anyone tried anything, and did it make it look better or worse?
Thanks for the link! Have read up on this and it sounds really good. It says it can be used for lenses but doesn't mention cameras. I suppose it's because of the electronics! I'm purchasing some off Ebay today. I'll try it on a lens first. If that's ok I'll use a sponge to apply a small amount to the camera.