Rayin "S",
You sound like you've done this before so please forgive me if you already know what I'm about to mention. It may be beneficial to others anyway.
I've used a number of different products over the years with varying results. I've used, BLECHE-WITE white wall cleaner for tires, fantastic household cleaner, 91% alcohol, & heavy duty Easy Off yellow can. One of these products actually made an HO Athearn trains SW1500 plastic shell brittle & brake up. It was either the brake fluid or Easy Off, I don't remember.
Since the paint is smooth & the lettering is off, which always shows when painted over because it's another layer of paint, just paint over, as John & others suggested. If you own, an airbrush it will give you better control & a thinner coat of paint and avoid blobbing up the details. If you only have access to rattle cans, I've had a lot of success with them, even when painting over pre-painted items. Warming up the paint can in a basin of warm water, for about 30 minutes, will help the paint flow on smoother. NOT HOT WATER! Even warming up the body with a hair dryer just before spraying will help with the paint flow. Humidity should be low. Flat paints will go on easier & thinner but will need a clear gloss coat if you intend to decal.
