I'm a little late to the party but wanted to toss these in.
VHT can look great but it's tough to get consistent results.
Despite the earlier claim powder coating may not look "original," it was apparently good enough for the MCACN judges a few years ago. The Commando valve covers featured are on a '65 Dart Charger that scored 996 out of a possible 1,000 points ... and the covers were not one of the deductions.
http://phoenixspecialtycoatings.com/gallery-of-work-samples.htmlThe same black wrinkle powder is used on my factory-style air cleaner restorations too.
As to needing 'perfect' metal for powder to look great, that depends on who does the work. I have never been a fan of traditional powder coating fillers -- they ALL suck lol (and prefer to do real bodywork rather than merely slopping some goo in there) -- but found something suitable several years ago that fits the bill on the rare occasions I use it.
I guess I've ignored this forum for too long and don't have enough posts to share any photos yet but my website has hundreds of them. Hit me up if you have questions or if I can help.