to do the 73 to 80 swap all you need to do is change out the control arms(A frames)to do this you will have to drill out the holes for the U bolts that hold the lower control arms on as the later ones are slightly larger diameter also you will need to install the later idler arm.the geometry is slightly different on the idler arms if you dont use the later one it can cam over and lock the steering all the way to one side.I learned all this the hard way.
