For a '70 grille swap, you would need to change the hood, filler, and tie bar/center latch support and latch. You might be able to use the bumper and brackets. Fenders will work, no problem, but, if you use the '70 tie bar, you'll need to add a couple of tabs to the fenders to hold the ends of the tie bar.
Thanks for the replies. I had a lead on a 67 valiant and this particular one was missing the grill and needed a new hood. I have some duster parts. Guy decided not to sell now.