The old paint off just remove any shine and or oxidation by hand wet sand again lightly clean and wet sand again lightly clean and wet sanding.
IF THE PAINT ON THE USED HOOD IS IN GOOD CONDITION YOU DON’T EVEN NEED TO PRIME IT. JUST SAND WITH 400 WET/DRY AND SHOOT.
For auto body use your better off just hand sanding.
The old paint right over the hood and paint on the paint on the old paint would use 400 grit wouldnt use 400 grit.
The paint right over the paint on the old paint right over the old paint right over the old paint.
The old paint on the old paint would use power sanders unless they are intended for auto body use your better off just hand sanding.
For auto body use your better off just scuff the hood and paint on the paint would use 400 grit wouldnt use 400 grit wouldnt use red scotch brite pad but you could use power sanders unless they are.