After having demo'd and sold thousands of "receivers" in a Retail environment from the mid 70's to the end of the 80's (Technics, Toshiba, Rotel, Pioneer, Luxman, NAD,Telefunken, Phillips and more) ... My opinion is that they Did Not sound Great then, and the addition of 40 or 50 years has Not Done Anything to improve their "Good, but thin and unromantic" sound. High End separates, many integrated amps and custom equipment, generally (by a WIDE) margin, sounded better and represented a more accurate presentation of the intended sound.
The Golden Age receivers were often Attractive, Well Built and sported Great Specs.... but that all came at a cost due to the very competative nature of the Business and the pursuit of Great Numbers, not Great Sound.