This looks like it may be an exceptionally nice Riv GS - it is pricey but probably one of the nicer ones we have seen. Wish it had the white interior and white top or no vinyl top https://losangeles.craigslist.org/wst/cto/d/san-pedro-1972-buick-riviera/6974537635.html
The owner needs to attend to some minor details, ie: hoses, clamps, heat tube, etc. I do love the color and agree, white in place of the black top/interior would have really set that one off.
I question if it is a real GS . New emblems do not make it a GS. It must have a rear sway bar, large diameter a/c compressor pulley due to the standard 3.42 posi rear in a GS and chrome air cleaner lid. Very nice car though.