Syd MeadAmong Mel Francis' albums
I'm going out on a limb here, but the number 280 coincides nicely with a wheelbase of 280cm, just about right for a 110" wheelbase mid-engine car. Lots of room for a mid-placement Viper engine mounted on a G50 Porsche transaxle!
Ahh, if limousines just looked like this..... The designation 400 might be based on a wheelbase reference, since 400cm is about 158" and photoscaling based on a 74" driver height would indicate this wheelbase to be around 160".