I can't quite tell if the fuel tank bump is there in Earls pics or not. There is something dark there, but I'm not sure if it is the fuel tank bulge or the fender of the car behind it. There is something that could be the right side of the downslope of the bulge, but I have not looked at it with my magnifiers. It does not look high enough in relation to the headrest nacelle, though.
There is also the fact that most of the 375 pluses were raced - although the amazingly attractive yellow with green interior car was not.
Good point about the variants... Scaglietti, Pinninfarina, Bertone, and all those other coachbuilders just had waaaay too much fun!
I suppose I could lean towards the 375 Plus.
Steve