Changing the body color

I just went through this. As others have stated, many body shops won't paint someone else's work. I just went through this myself. My father was a body man until about 25 yrs ago. He still did it on the side for a while but has isocyanate poisoning now. The paint on the car was in decent shape, so we hit it with 80 grit DA. Took the bad spots to metal and did necessary repairs. Primed and glazed the little spots we could find. Block sanded and re-primed, twice. From there we started looking for paint... Body shops didn't want to touch it. We ended up finding a very good painter and we wanted to let him do final sand so he could be sure the car was straight and ready for paint. He did find a few spots we missed or had accepted as good enough. In the end he had 80hrs of labor tied up into body work, 4 color paint, and cut and buff.