I happen to think the best results will cost you the best. Here is the motor in a friend's NCRS Top Flight/Bloomington Gold '67 435 convertible that received no deduction in shade/shine/luster from the judges. It is a custom mix, but man is it dead on.
Personally, I love the valve covers shined up nice, but the heads/block/oil pan dulled back.
-Dan
a little more bit exposed with the "shop" camera.
(PS- I had NOTHING to do with the over spray)