If you are going for a full repaint, the best bet would be to find someone that can sand (media) blast it for you. To repeat what others said, any amount of untreated rust WILL come back to haunt you.
Depending on your budget , I recently had a frame blasted, dipped and powder coated in a solid (stock) color for $140. The last time I rattle can painted a frame I invested about $60-$75 alone in materials, paint, solvents, sanding papers, ect.