The unraced F1 projects of 1978 can be found in this article. Just to make it a bit easier with an overview for everyone.
Riccardo Patrese, Zolder 1977, Shadow DN8
Unraced F1, rally and sportscars – 6 of the best
1978 Ralt RT1 Formula 2 HTP 31.12.2031
1978 Archieven
Williams, F1 UniONE CAREER by TiroweE Wiki
Unraced F1, rally and sportscars – 6 of the best
Unraced projects of the 1969 season
Racing Knights: 8 of the speediest sirs in motorsports - Hagerty Media
Projects 1970 - 1999 Archieven
Prost AP01B Archieven
Andretti Is Already Wind-Tunnel Testing for Its Unapproved F1 Program
Lightning 1976-1979 car-by-car histories
Lotus 76: the overlooked car that laid a path to F1 success - Motor Sport Magazine
March 782
Unforgettable Moment: Masami Kuwashima's 1976 Japan GP