Here's a pic of 65Dartman's Polys and Slant 6s still in progress ... I didn't have the plastic dip on yet but you get the idea.
View attachment 322527
The reason I usually put a little powder on the tops of the stovepipes and wrap the edge of the gasket rail is to prevent something known in the industry as "creep."
Any time there's bare metal open to the elements, moisture can get in between the cured powder and the substrate metal and eventually work its way throughout the entire part. It will effectively rust from the inside out ... and one day maybe twenty or thirty years down the road you'll be changing your valve cover gaskets, slip with the socket and hit the side of the valve cover. And a big chunk of the coating will come off in a sheet to reveal lots of rust underneath.
The average mil thickness of powder coating is 3-5 mils -- very thin -- so it generally does not interfere with breather cap / pcv grommet installation. But having it there where the factory never did is just a small measure of extra rust prevention to keep your parts looking fabulous for decades into the future.
There really is a method to my madness. :-D It's just not always readily apparent.
Thanks for the opinions so far guys! Let's keep them coming -- I know there's at least another 25 sets out there that can be evaluated.