Have any pictures ever turned up of Ray May's '68 Vette in Steelers trim? When you spoke to Ray did he mention where in Pittsburgh he originally purchased his 'Vette?
Would be pretty wild if it happened to be at "Washington County's Largest Volume Corvette Dealer" Yenko Chevrolet...then there'd be a Yenko/Motion out there somewhere.
Could have been any number of Pittsburgh areas dealers, but Grabiak Chevrolet in New Alexandria comes to mind as well, as they've been a high volume Corvette dealer for years.
Good luck in your search Larry, your persistence will pay off eventually.