For receivers, The 1974,75 Pioneer SX-939 and SX-1010 are highly regarded. The 1976,77 Pioneer SX-950 and SX-1050 would be a good choice. The 1978,79 Pioneer SX-980 or SX-1080 would be fine as well. The Sansui G series from the late 70's are well received. G-7000 or G-8000 are good sounding and a good size. You could try separates, The Sansui AU-717 is a great sounding amp. Pair it with the TU-717 tuner and you have the same as a receiver that sounds better. Even better, but way more expensive, would be the BA-3000, CA-3000 combo paired with a TU-9900.
I would advise to get the AU-717 and TU-717. They have a great sound and still aren't that expensive. All the problems are well documented. Count on spending about $100 Dollars more than the expense of the units for parts. Replacing the capacitors and some diodes and some transistors, a new relay and the unit will last another thirty years. They both sold extremely well in the seventies, so they are all over ebay. If you search the web and read up on them you will see what I mean. Audiokarma has threads on overhauling them. They detail the problems and solutions, give part numbers and all. If you get a pair you will not regret it. Unless you decide everything else has to be upgraded. That's a slippery slope.