If you plan on a stock color repaint, these are tricky due to the layering of the paints. A single non-stock color can be done by anyone with some patience, and care, and a wee bit of practice.
If it were me, I would now strip the tank to bare metal as you can't tell how much of the stock paint may have suffered from the heat. Relying on it now to provide proper adhesion for repainted layers is optimistic. Not required, but it's how I'd do it.
Use Aircraft stripper to chemically strip the tank. Then, 320 grit or Green ScothBrite pads on a grinder, and sand down the remnants. Then, degrease the surface with acetone. Shoot etching primer. A quick block sanding with 400 grit to scuff it a bit. Then shoot your colors, followed by 2-4 light coats of clear. Once the clear has cured, wet sand with 1500 grit, then 2500 grit. Follow with a buffing compound. VoilĂ ! Old Jed's a Millionaire-
I may have a petcock for you. Shoot me a picture of yours, and I'll see if mine is compatible.