The thing I don't like about the GT40 is its ugly sides. The windows go straight to the sidelines, needlessly increasing frontal area, and making it kinda ugle. Most replica's are of the Gulf version, with only two instead of four taillights 9Much better looking). The MKIV though, is much more curvy and nice.
Do to dispalcement difference, Ferrari realy was pushing what they could come up for aero. They where the leaders in body design at he time. Several finaly caught on to Ferrari's advantage, and started to work on such things to, such as the MKIV GT40, Dayton Cobra, various non production racing E-types, etc. Porsche was on it from pretty much their early days, wich is also how they did so well from engines that where of such small displacement.
Its not a bad way, gives i a very agressive stance. A production car to pull that look off would be the Countach, but they slopped in the sidelines even more, making them flow into the rear end.
I think the GT40's were at least 7L, vs the 2L Porsche 8's, and the 4L Ferrari V12's, hence why the other two put such stress on the bodywork.