Fiberfab claimed to support the Corvair engine/transaxle(?) in the Avenger. I never saw or heard of one being assembled, but I thought it a good enough idea that I had started accumilating Corvair hot-rod gear in preparation for the event...which never happened, of course....
I could be mistaken, but IIRC the Corvair conversion used the VW pan and just reworked the chassis to accept the Corvair engine...might have even adapted to the VW transaxle, I don't recall the exact mechanism, but I recall clearly that there was that Corvair option.
The Valkyrie did use a tube frame with the mid-engine V-8 option...I saw one in Denver, CO.
The kit that interested me more was the V-8/Corvair conversion...a small block Chebby V-8 replaced the back seat and joined to the Corvair transaxle in a second-generation Corvair. I suspect there might still be some around...the name "V-8 Archie" comes to mind...but now I think he is more associated with V-8/Fiero combinations.
Geez....these memories are so old they are hard to....uh, I don't know, I forgot :embarassed: !
Have you tried the various Fiberfab, Avenger, Valkyrie forums elsewhere? They might be of more assistance.
Cheers from Doug!