Not totaly insane but insane just the same. I can see the truck in my minds eye and it looks prety cool. Please keep in mind making the back doors is going to be a big deal. Maybe instead of making her a four door cab maybe you could build an extended cab. I know the job can be done because I saw where someone else built a tilt back or slant back truck using the same era chevy cab and making it a four door.
Good Luck
Good Luck