Or, if the paint job is decent but too glossy, why not spray with Dullcote?
+1 Winston Smith. This is the easiest solution of all. Do you have photos of the originals to share?
Removing paint from small miniatures, especially tenacious paints like enamels, is a lot of messy, smelly trouble, and exposes you to nasty chemicals. In the end it's often impossible to get all the original paint out of the tiny nooks and crannies and crevices anyway, and the process destroys most glued joints (masts? boats? basing?). I've found it's usually cheaper to sell off the unwanted models and just buy bare lead to start over the "right" way (however I currently define that…).
This is a judgement call, but I have been able to work miracles with very poor previous paint jobs by simply overpainting and revarnishing. If the original paint is too thick and obscures details, this is not going to work, but given the rather crude nature of most 1/3000 naval models, I bet some drybrushing, washes, lining, and perhaps an overpaint of the occasional badly-colored surface would be more than adequate.
If you just don't have an eye for that, another option is to simply primer over the gloss enamel. I have found Testors and Tamiya primers (both brush-on and spray) stick really tenaciously to previous gloss enamel coats (I prefer Testors/Model Master because it flows better and goes on thinner). This method will thicken the layers of paint even more than a light overpaint/stain/drybrushing, but if the original paint isn't thick enough to obscure the cast-in details, it should work.
I've also used a combination of these techniques in salvage operations (re-primer and then repaint some surfaces, overpaint or stain/wash/drybrush other surfaces, line and touch up specific detail spots, etc.).
Another reason to keep the original paint is that those gloss enamels make an extremely tough protective layer. If you also seal the bottoms, there should be no way for the lead to oxidize from the inside out (which can be a concern with castings from 30-50 years ago…).
- Ix