Cleaning paint off of tail light lenses

I received a new set of tail light lenses for my 68 barracuda, only problem is that who ever had them before did not want the back-up lights to shine through the lenses so he painted the inside white BLACK!!! Does anyone have a good solution that I can use to remove the paint without hurting the lens. It just looks like he taped them off and sprayed them flat black.
Thanks
Bob

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