For AVRs, I would be looking at Denon, Marantz, or Yamaha. You should end up with a decent one for 700 to 800 from those brands. About the KLH speakers.. time, and speaker science, has moved on since those speakers were a contemporary design. I wouldn't use those for front stage speakers. They might work for rear surrounds maybe. KLH was not a bad brand back in the day, but these days I would look into getting some beefy bookshelf speakers to be used as front stage speakers. You might look at
Hsu CCB-8s,
Ascend CMT-340s, or maybe
SVS Ultras. If you get a AVR with pre-outs, consider some
JBL LSR308 speakers.
For side surrounds and back surrounds, you might think about in-wall speakers rather than in-ceiling speakers. If you want a Dolby Atmos or DTS:X system, use in-ceiling speakers for the height channels. For subwoofers, consider
any of these as a starting point- I would get two, at least.