I would clean it up and lizardskin the roof and then topcoat with whatever color you desire.
I say this for one reason, you can spray 2 pieces of sheet metal with black paint, with one having LizardSkin CI on the back, leave it in direct sun for an hour, the metal without the LS will be hot enough to raise blisters, the insulated sheet will actually feel COOL to the touch! And the reverse applies when a block of ice is put on the metal plate, it doesnt xmitt the cold either.
My civic project car was blasted of any corrosion, chassiesaver applied and then both LizardSkin thermal and sound insulation applied to the entire interior followed by MonstaLiner on the cab floor and spare tire well. It was tomb quiet inside with the windows up and the AC had to barely work at all.

