what would it cost? 4 door '72 Valiant rust repair.

Say someone has a '72 Valiant 4dr that he just likes alot but it has a rusted torsion bar crossmember, rusty front floors, and rusted front frame rails and wants to get the car repaired. I guess a complete front clip would be the best way to fix it but not the only way. What would someone expect to pay to have a job like this done on this '72 Valiant?