I would agree but not nearly as difficult to find as the tri shield for a 70. Check eBay. They pop up from time to time.
Make sure he does not mistake the one he needs with the later year type that has the studs built into the base of the mirror.
Jim my door is drilled for a mirror already(like that when I purchased car). Are you saying the earlier one's (70-74) are different than the early 80's ones I see on Ebay?
I believe the big car mirrors had the studs. They would not sit right on the A body. Like this one. https://www.ebay.com/itm/1977-1979-...675266?hash=item1ed59a41c2:g:PWMAAOSwETJaHyGB
That is my understanding. The early 70s have a mounting plate that attaches with sheet metal screws from the outside and then a gasket. By 77 the studs were attached the mirror and the retaining nuts were applied from inside the door.
