Hybrid Tube Radio

Hi there,
In the glass audio article mentioned in this thread, I am wondering if anyone has any ideas on what to do for a speaker.
The author used an Audax 4" and tweeter, but the woofer is no longer made. I was thinking instead, of trying a full range 4" driver such as the FE103E, but also have to consider keeping the enclosure quite small (12" x 6" x 8" or so).
Does anyone have any suggestions?