I'd like to add to the comments here;

First of all I've found that original flavored Pinesol removes paint from plastic quite well. Once the paint is loosened use a stiff bristle brush to whisk as much of it off the model as you can submersed in the Pinesol because it seems to smear back onto the model once the Pinesol is washed way under warm water. Then I put the parts in my ultra sonic cleaner filled with Windex (again original flavor). While plastic doesn't clean up in an Ultrasonic cleaner quite as well as metal it does help remove loose particles. Finally rinse everything in warm water (soapy is optional). This is a long-term job, which can take a few days to complete.

Naturally test your plastic in the Pinesol and Windex first! I've stripped Athearn and Life-Like in this manner.

As a professional painter I'd like to debunk a bit of the mythology about Air Honing (sand blasting) plastic; we seem to have this kid glove mentality about it. I Air Honed 4 plastic diesel shells yesterday (right along with a couple of brass pieces) in my Harbor Freight blasting cabinet. I used 220 grit silicon at between 80 and 140 psi (depending on how far down the air use pulled it)! The shells came out clean with NO damage to any of the plastic or detail. I think we either don't understand or we forget that silicon cuts rather than beats and the harder the surface the better it cuts (up to a point, of course). The softer a material is (again up to a point) the more the particles tend to bounce rather than cut.

You are all quite welcome to continue to use messy, ineffective, and long term baking soda if you wish but I tell you from hard experience that it is a waste of time when the silicon at a rather high pressure works great. Again I have not air honed every type of plastic so I would encourage you to test it first - but I say that more as a disclaimer. Athearn and Proto-2000 I've found to be quite safe!

As far as removing lettering I think the tool Jack Burgess mentions in his RMC article would be perfect with the silicon for this. Or the Paache Air Eraser. But if you use the baking soda prepare to be there "alllllllll daaaaaaay long"! Grrrrr.

Derrell