I have a set of TP Engineering rocker boxes; they look a lot like yours.
www.tpeng.com
Have a look and see what you think, Tux

hit Google with US Pat 6672294, comes up with the Inventor and his Address

Hmmmm, accessing the old memory banks. I thought they might be Arlen Ness. They aren't on his site anymore, but if you send them a photo, maybe they'd recognize them. Ness has dropped most engine parts nowdays.

I checked my TP Engineering Pro Vent rocker boxes and they have the same patent number.