In my humble opinion.... this stuff is better. New formulations nowadays yield better end-user results :
http://www.caswellplating.com/aids/rustbullet.html
As far as my uses with POR-15 go..... it's good for a frame coating maybe... but nothing I'd want on my valve covers. Frames are rarely seen, and valve covers are right there on top of the engine. Powder coating is definately the way to go with it assuming you want a powder coated finish (some guys like to polish them, others like an anodize).
Check out everything here for inspiration :
http://www.caswellplating.com/bbs/al...t.php?cat_id=2 . There's some nice work in there to give you some ideas.
'57 Olds,huh? Stock survivor or a custom job? Just curious.