I measured a stock 1970 car steering wheel depth at 2 3/4". However, I felt like the steering wheel was too close and I understand the steering wheel was moved away in later cars. So I put the seat in my car and loosely mounted the steering column and found an optimal comfortable position for the steering wheel.
However, I have the seat back as far as it will go and it feels like the pedals are too close. I'm thinking I could move them down about 1" but that's probably the limit. Reducing the travel might be a good thing. The clutch pedal has 7" of travel (from pedal to floor) and about 1 7/8" at the push rod. I am using a hydraulic cylinder that has a max travel of 1.4". So, loosing an inch of travel might be a good thing. The brake pedal should be pretty easy as it is limited by the switch which has plenty of adjustment.