Effect of raising rear of car?

I think you are probably right about this detail. Mainly, they were trying to avoid the nose lifting at speedway speeds. My Mopar Suspension book says something similar about raking the car 1 or 1-1/2 degrees, though I think they recommended dropping the nose. But most aerodynamic tweaks don't really apply to most street cars at realistic speeds.

FWIW, my Barracuda fastback generates a lot of nose lift at speed, due to the airfoil silhouette. I just grabbed a plastic air dam off an 80s GM to try mounting under the rad support, on the recommendation of a guy I met at a show.

MOPEkidD-3 said

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Also about the aerodynamics part I got it from a documentary on NASCAR in the '50s-70s, it said how racers found that raising the rear slightly so the angle was just a few degrees up (nothing drastic or even very noticeable) made the car much more stable at high speeds...

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