I'm wondering if the double stacking of two different speaker designs is a good idea or not?
I agree you will need some kind of larger speaker setup that matches well to your tube amp to match what you have in that regard and that may not come cheap if they must do better in all regards compared to what you have.
Rather than replacing both, how about trying adding a pair of good subwoofers to just the Forte's or the others, whichever you like best?
Maybe that in conjunction with some tweaks to fine tune the sound might fit the bill well.
Other than that, something like the AudioKinesis Jazz modules come to mind.
Or a pair of Klipschorns maybe if they would fit into your room.
If the larger CJ amp can handle less efficient speakers with more challenging impedance curves, then a pair of OHM Walsh speakers might be worth looking into. If not, then even a smaller pair of OHMs + subwoofer would likely not leave much for wanting.