I think for the size room you have a pair of really good Peerless sandwich cone 8 inchers would be good, I used them in my hybrid electrostatic cabinets ad they were wonderful
I had the 10" version with my B&Ws (in NHT Sw2Si cabinets and some extra bracing and stuffing, for years but recently found really rare B&W DM 16 woofers. These used the early 801 magnets, frames, and coils, but are 11 rather than 12 inches.