I am also looking into building another car. I saw a 1957 Porsche Cabriolet replica that uses the same basic design the F5 is looking at, using the Subie drivetrain as a mid-engine platform in a tube frame. The only problem is they are not available as a kit. They will build and paint a roller and sell it to you and then sell you an engine which they will install for you. Sound familiar? They've been building them for years.
http://www.specialtyauto.com/PORSCHE.htm