bumper interchange?
Thats what I thought and is why the bumper is so far out. I don't know my valiants to well. I am sure some one will know but I would think as long as you use the brackets off of a 73 it should work. Though the mounting locations for the brackets will not be on your car and will need fabed up.
Like I said I am not 100% on this so I would wait to here from some one else who can back this up.