Those are very natural sounding speakers, with especially nice midrange response. If you can match a center channel speaker (good luck), they'll work fine. The 105.4 had a somewhat bloated midbass, and crossing out of them and using a subwoofer will make them even better. Headroom is limited by the lower range of that 4" Bextrene mid...be careful. Excellent speaker...
(The Kef 107 from a few years later was an astonishing full-range loudspeaker with possibly the best deep bass of any consumer loudspeaker at the time.)
(The Kef 107 from a few years later was an astonishing full-range loudspeaker with possibly the best deep bass of any consumer loudspeaker at the time.)