Need help with Panel Beating

Not really my area of experience or skill but...
See if your library has Robert L. Sargent. Automotive Sheet Metal Repair
Its an older book that seems pretty good for how to approach and develop your own answers for questions like this.
I picked my copy up at a used book store and it has way more in depth than SA and even HP books that I own or have looked at.

@Ddaddy may have some insights into prepping the surface for a vynil top.