Slide the seat in with the new column and steering wheel in place and sit in the seat, move it around to where you like it and mount it there
I like to move the seat as far as comfortable to the center and as far back as my legs will safely reach the peddles of the car for two reasons, one is moving weight to the passenger side and the other is more arm room from those dang, pesky door bars
Think twice, modify once
Same thing on the shifter, put it where you like it