Auto body repair & detailing: Removing extra coats of paint!, maaco paint job, quality paint job

Question
My 1971 Ford T-Bird has had three coats of paint over the years, the factory original and two additional coats by MAACO.  I paid for the best preparation (sanding) and the best paint and after five or six years, the last coat of paint is still real nice and isn't peeling off as all the other body shops advised me it would. I have had to have some dents removed and sheet metal work done on both rear fenders due to rust damage.  I need to have it painted again to make it look good.  I doubt if there is a shop in the state of Washington that will touch my car because of MAACO painting it.  The local Ford dealer will do a repaint (they do really nice work)but asks an extra $1,400.00 to strip all the paint off as they claim that only a nut would paint over a MAACO paint job!  I am going to remove the last two coats of paint and am not sure how to proceed.  I have been advised to use a fairly course sand paper to remove most of the paint and then finish up with fine.  I have been advised not to sand down to bare metal although I don't understand why not!  I am going to use the best quality primer available (white).  If I get down to the original paint, Ford will do a quality paint job for around $1,200.00.  I need to know how I should proceed!  I am sure that using a course sandpaper will make fairly short work of the paint removal.  I have a new top (vinyl) which required extensive rust work and looks real nice.  Is it OK to sand down to bare metal and finish with wet sanding or should I be careful not to go to bare metal?  

Answer
  hi melvin,
     if it is sanded with 180 grit on air DA sander this should be all that is needed  to be done. this will remove a couple of layers of paint and if you sand through the paint all you have to do is prime the area a couple of times letting it dry in between coats this will level the paint back up. thanks for writing. you should prime or seal the car after you sand with 180. if you use a primer, sand with 320 by hand. if you use a sealer use a nonsanding sealer. then paint. thanks for writing.