Black was a bad color choice for a hull bottom on a neutral colored boat. Scratches will show up in bold relief.
The lay-up schedule (Tuff-weave) is immaterial. You will be applying new paint over either gel coat (if you strip the existing paint) or over old paint.
I would attempt to strip the old paint first. I have had generally good results with citrus strippers although multiple applications and some sanding are often required.
As for paints, there are lots of options. Two part polyurethanes like Interlux Perfection are probably the toughest. I have had decent results with Interlux Brightsides (one part polyurethane) but my current favorite is Pettit EasyPoxy. I would choose a color that approximates that of the gel coat on the boat as it will make the inevitable scratches less apparent.
Selling it put anything on it. keeping Interlux is way to go. It’s very hard to sand off I was amazed when I had with Porter Cable orbital sander. On one hull 12 years yellow faded a bit but still a brilliant shine. Unless you look where sun doesn’t get sun you’d think it was that color. 8-10’ you’d think it was a new hull.
Those Jensen 18’s are a great day trip canoe when you want to be out just having fun zipping around a lake. I think of them as the tandem version of a solo Advantage.