Thanks to Michael Porter, I have identified the TR3 mystery cam.
It was done by American Cam Grinding in LA back in the early 80s.
According to the guy I talked to at their shop, it was a popular hot
street grind "back in the day" and is still pretty popular now. I happen
to have the engine for my TR3 in the shop waiting to be reassembled, so
this will probably go into that one. When I took it out of the box it was
wrapped in a LA racing sheet from 1982, so that's how long it's been
sitting around waiting for a home. Don