Yes I used to have a black velvet interior but didn't like it.
My car had a white interior from the factory, I alwats loved white interiors and decided to put one back into the car ; I found this one in quite good shape, but it comes from a Swiss imported Challenger I guess, that had power windows, I heard it is a rare option.
I didn't know that cut was for the seat belts though, do you have a picture of how it is done ?
My car from the factory looked like this, without the R/T package (striping...) :