Always better to go to bare metal. Big job on a engine if not on stand. Any chip offs will show bright orange. If the orange is the wrong paint or not cured properly it will give up. If a real nice restoration effort underway...gotta go to bare metal otherwise no guarantees. Even if paint first with POR 15 system there is no guarantee without bare metal.
If just a driver, won't hurt to try a paint over. just labor.


Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn