If you are not limited to cabinet size, I found a pair of Sansui SP-300 speakers are well-matched to older receivers with somewhat low damping factor. I have a pair of 1968 vintage SP-300s, I bought from the original owner a couple of months back. I use a Pioneer QX-949 quadraphonic receiver to power them. I had and sold four pairs of older Sansui speakers, but these I will keep.
They are very efficient speakers , and like the Heresy speakers, feature horns. I wouldn't worry about the 50W power-handling spec.
Nando.