Getting ready to apply body filler on my 72 dart swinger . The roof HAD a vinyl on it but was removed by p o. AS expected there are a million tiny pits . Some fill with high build primer (from a spray can) others are deeper. What brand,what type(light weght,regular) is best.?? I used the spray primer to see if it would work . I have epoxy primer to use when ready. Ever coat has several varieties,others do also. Always used bondo before. THOUGHTS please!!