There are several great speakers from those two decades, but I'd go for something iconic.
If you want an "ultimate '70s system" AR3s, or AR1Ws with Janzen tweeters... maybe just a pair of Janzen two ways. Allison 1,2,or3s, or Dahlquist DQ10s,or 20s would also be excellent. For an early '80s system, I'd go with Ohm Walsh (any from 1-4), or maybe AR9s... but 9s really need a bit more amp. If you want to add a turntable, I'd go Thorens for the '70s, or Rega P3 for the '80s.
Cliff
If you want an "ultimate '70s system" AR3s, or AR1Ws with Janzen tweeters... maybe just a pair of Janzen two ways. Allison 1,2,or3s, or Dahlquist DQ10s,or 20s would also be excellent. For an early '80s system, I'd go with Ohm Walsh (any from 1-4), or maybe AR9s... but 9s really need a bit more amp. If you want to add a turntable, I'd go Thorens for the '70s, or Rega P3 for the '80s.
Cliff