I ran my lines on the outside on my 81, that's where they were anyways, and all (except very old vehicles) have 2 piece steering shafts so that when you have a frontend collision it will colapse instead of pushing into your chest killing you. They are held in place by a pin that if you remove the pin it will allow you to extend it out.
The third gen trucks have one piece steering shafts with the accordian that collapses in an accident.
That will work DTB. That is what I did except I added my extension on the other end of the shaft.
Why do you need to cut out that crossmember in the back? My shock hoop fits easily behind the round crossmember.