Strictly the F1 isn't the secondgeneration Pantah engine.
After the first 1979 series (red fairing) came the better gearbox and clutch and 600s.
Mid eighties Cagiva used the 350s and dryclutch 650, same crankcases as the Ducati Indiana.
The F1 is just the ULTIMATE Pantah
After Ducati used the Darmah (tigre in the tv series Sandokan) they came up with the Pantah (the first morse chained belt letterboxfairing ) the Utah and the Rollah (chopped Pantah not unlike the recent Borile).
Guess they wanted to develop a serie of (partly compatible) bikes with similarsounding names just like the waterpumps that all had names of a tree and just before they started cashing in on the MHR name story.
At about the same time everyone started using names instead of types, Ducati couldn't stay behind.
ciao
ducadini