Sure there probably were some bad sounding products put out in the 1970s, but there were also some very good sounding products too. I'm thinking Luxman, Sansui, Kenwood, some Sonys, Yamaha, Hitachi (mosfets only), Marantz, Pioneer, Nikko and even some Toshibas are highly functional and decent sounding units. You can find these units for under $100 in any urban area. If you want to go crazy spend another $200-300 and have them recapped and aligned. Now pair them with an appropriately easy speaker load and while you won't get 21st century audiophile approved sound, you will get something quite listenable.
BTW, the tuner section on some of the receivers are better than all but the best modern designs.
BTW, the tuner section on some of the receivers are better than all but the best modern designs.