I know a little about painting these cars.
You do not need to go to bare metal unless you have visible rust.
Just take off the lousy repaint and get into the original a bit trying very hard Not to blow through to bare metal. Nothing is better than good factory primer.
Unless you plan to take every square inch of paint off to bare metal, don't blow through.
Hit it with 220 then 320 to prep for primer/sealer.
And Tremulune,
Lay off the whiskey
