I just finished fixing 3 dents, painting, and remounting my tank today. I had  a 2 inch round dent on the corner of the tank, just below the fuel cap, a large, oilcan-type dent on the right top (back from fuel cap) and a smaller impact crease type dent, also on the top of the tank.
Used an air DA with 80 grit to buz paint off, assess the dents, and create a rough surface for adhesion. I felt I could probably pop the large dent and did so with compressed air which resulted in a much smaller dent to fill. I then filled the dents with a marine epoxy called Marine-Tex. I again buzzed it down with 80 grit and found that I was pretty close, so I used Evercoat green scratch filler (a polyester fill that sands easily to very thin and sticks!) that I DA'd with 80 then 180 and then hand wet-sanded with 220.
I used Rustoleum (rattle-can) Painter's Touch wildflower blue satin finish (can't help that I'm a cheapskate!)
I'm pretty sure the durability of the paint will suck but the paintjob was cheap enough at less than $15.
I also welded up the taillight holes in the rear fender, ground it and used almost no filler to make the top of the fender smooth. I have mounted a lucas-style taillight and new plate bracket on the original license light mount under the fender (after cutting away the original plate bracket. The fender and taillight now resemble the setup on a Harley with a factory bob-style fender.