The first car that my brother and I owned was a '47 Plymouth, 4-door sedan with suicide doors. This discussion made me remember that we cut the squared rear wheel opening out to a rounded shape. It's been to long ago to remember why. A lot of strange things were done in the 60's.

Although I really like the look of the black Plymouth coupe that's sitting real low (air bags in the parked position), I found out when I started building my car that it was not possible to remove the rear tires without taking the coil-overs loose, at the minimum, but it may have also required unhooking the brake flex lines and maybe the drive shaft, to get the rear end to drop low enough to get the tires off. To avoid that, I altered the wheel opening, but as it turned out, the modification required was so minor that most people would not notice the slightly different shape.

In the end, you should get the look that you want. You're building the car. Please yourself.