I am also a classical music soul. If you already know you are thrilled with the Naim sound, I would go used with a Naim Nait 5i integrated with a Naim Nait CD 5i cd player. You can find the integrated for around $900 and the cd player for around $800. That would leave you around $1,300 for speakers. There are a lot of good speakers out there for that price. I tend to like monitors for their soundstage and detail. In this price range I would suggest the Focal JM-Labs 807V. Harbeth 7ES may be found used at this price and would be excellent. Any Spendor speaker should match well.
If you want floorstanders, I think any of the PSB Stratus or Platinum series would do well. I personally liked the Stratus Silver best. Also, a dark horse, that I auditioned and found to be a great classical speaker, is the B&W DM 604.
For classical music, if I had the room, I would buy Magnepan 1.6's. They are, by far, the best sounding speakers, for classical, to my ears. You can find them used for around $1,200. However, they probably won't work well with Naim. They, reputedly take a lot of power. I heard them with a 50 wpc integrated and I fell in love with the sound. Also, they take a lot of room, something I don't have. Don't know from the description of your room whether or not they will work. I believe if you paired these with a NAD C372 and one of the better NAD CD player, you would have a system to cause me to be envious.
Good luck, you've got a pretty good budget for stereo and all the suggestions look pretty good to me.
John