Filler primer

I will try answering the question the best I can with out pics and vague info concerning metal straightness and condition.......

After ya get two coats of epoxy down let it sit over nite then tack rag following with 3 wet coats of urethane primer if the vehicle is straight and ready for final blocking. Stay in the recoat and forget sanding the epoxy if ya can help it. The chemical adhesion will be fine without sanding. And don't depend on epoxy to sub for high build please.
Hope this answered your questions concerning your primer in hand and what to use on top of the epoxy. Try to stay within the system if possible. Good Luck :glasses7: