Speakers for Outlaw RR2150?

I would look into these, I think they go on sale from time to time but have gotten some rave reviews:

GoldenEar Technology Triton Two (or Triton Three)

otherwise I would recommend Vandersteen whatever he likes in the price range

I have the amp and love it with Sound Dynamic 300ti speakers but good luck finding a pair and they are monitors anyway...

lots of choices-
for vintage character maybe a classic: Klipsch Heresy but get the most recent Mk III model which is available new for about 1500. I think that would be a great choice.

I would try to get a little more input from your friend as to what type of sound he likes. We can all tell you what we like, but your friend has to listen to the speakers, not us. Also, I wouldn't worry about the speakers being a 3 way, and not something else. Its all about the design and build quality. So many factors go into making a speaker, just picking something because its a 3 way over a 2 way (or whatever), will in no way tell you how the speakers will sound.

I use this receiver with ADS L-1290/2 speakers in my gym/shop. They mate beautifully. Three-way floor-standers from the mid-1980s, this model is a great value on the used market, usually priced around $4-500. They look nice, too, with a small footprint. If you're unfamiliar, do a quick search on the web. Lots of fans out there.