Don't strip the old paint, scuff it with a grit recommended on the primer can, clean it well, wear a mask and spray it. Leaving paint instead of just primer will offer better rust protection. Primer can be porous, not sealing well.

Have you considered getting rattle cans in the correct color for the doors and hood instead of primer?

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer