David, the Valkyrie was the very first mid-engined car I saw...and I was instantly hooked! I saw one on a car lot in Denver, CO and couldn't help myself...and I dared anyone to try to pry me away from it. If truth be told, I was a bit timid about looking too long because it was on a used car lot and it was night, so I was a bit paranoid that the law might think I was trying to steal it. At that time there was no RCR or Superformance, but IIRC there might have been the ERA, although I never saw one. The closest competitor was Kelmark with it's Dino 246 replica (who also marketed their Dino kit to be used with the engine and FWD automatic out of an Olds Toronado), followed by the other two companies who took over the Dino platform when Kelmark folded...Manta (?) and Magnum. Crown also sold a kit that allowed a SBC to be mounted mid-engined in a Corvair, IIRC...bet those didn't last long (would have loved to hear what Ralph Nader had to say about THAT combo)!!!!!
I'll be following your build...love the early replicas, even though they aren't "State of the Art" like we have now. I remember when the only readily available Cobra replica had a VW engine in it...yes, I'm THAT OLD!!!!!!
Cheers from Doug!!!