I think it is a GREAT idea! Why waste a good vinyl top??? A vinyl top sees very little wear.

As far as tips, pick your choice of dye and follow the directions to a "T"

I think I used "Marhyde" in 1984 on my top. At the time, I found a new tan top for my car and on it went. Sprayed it black and it still looks new today. I did use flattening agent so that it would not be so shiny and was/am happy with the result