Just remember, if the metal is flexing while you are blocking, you are making waves. Let the paper do the work.
You will likely need to prime and block several times.
Hey 68, excellent point on the metal flex.....I should have mentioned that in my response....soft easy multidirectional strokes, and yes, let the paper do the work, and just to be on the same page, and not at all critical, I use PPG-K36 primer/surfacer. Blocking out primer would be a chore.
Old Dart 66