Actually, the 72-74 fender headlamp inserts are correct for the 4 headlamp setup. I use 72-74 headlamp inserts and weld them into 70 fenders to make 71 fenders.
You will need the headlamp mounts which are being reproduced by P&G ($299) along with the 5" seal beams, retainer rings and adjusters. To make it look right though, you will need the 71 valance (P&G $499), valance insert (Year One $144), the 71 style park lamps (P&G $299) and lenses (Year One $154) and if you don't have them you'll need the headlamp rings that mount to the grille, (P&G $195). Will cost a little over $1500 plus the cost of the grille. You will need to slot the holes on your bumper brackets where they bolt to the frame and slide your bumpers in approx. one inch.
There's basically no fabrication, just installation.
Or...you could sell the grille to me as a spare for my 71.