$3500 floor standing speakers used. What would be your choice ?

The Sonus Faber Sonetto V's are a bit more dynamic on the top end than the older Sonus speakers and could be just what you are looking for. Even better if you could afford Olympicas or Serafinos. You should however hear them first.

I had the Bolero's many years ago... good speakers!   I also like the Proac and Tannoy suggestions.  Just make sure you get speakers efficient enough to pair with 60 WPC tube amp.

Just saw some Tannoy on TMR today.  Real close to your original 3500. Nice cabinet

Open baffles open and relaxed if you have room.  Won't be a problem driving them.

Many speakers take too much power.  

+1 for Totem.   Tremendous value and all around excellent speakers.   Super easy to drive.   Might look at the Bison Towers or similar.

The OP’s description in his second post says ProAc just like his initial post. Just make sure you get enough juice from your tube amp.