On a standard 1500 with stock low back seats, and from the floor to the top of the cushions, the heights are 34.5 mm front and 26.5 mm rear.
The runners for the seats rise from the floor at the rear to 4 mm at the front. You should fit the seats so that they rise as they are moved forwards, so that short people can drive the car.
The distance from the top of the seat cushion to the bottom of the steering wheel at the front is 12 mm. You should, of course, have at least that much so that you can get your legs in easily.
You should check that when your new seats are fitted, that you have full length, comfortable support for your thighs.
If, when you sit in the car all your weight is taken at the bum only, your bum will become sore and uncomfortable very quickly.
I recently fitted a set of seats from an unknown car, by welding them to the old seat frames of my 1500. They are a bit too high, but that's not a real problem.
