Elixirs will give him an almost flatwound thump, yet still retain the roundwound sustain. But at about $40 a set, he may not want to spend that much.
LaBella flats or Rotosound 77 flats will give a nice thump, and I think would fit right in with the CCR, Stones and Beatle music.
Then, there's always the old standby: Fender 9050 flats.
Nice bottom, and probably one of the least expensive sets out there. The Roto 77s would probably have the most mids.
I mentioned mostly flats, because I think they sound great on a Precision-type bass, and I like the way they record.
Good luck.
Mike
