Sorry about the iPhone upside-down business. LOL
I am 95% done routing this, the full $4000-$FFFF address space is available, but POKEY can be addressed at $0400-$047F and $0500-$057F (I hope this http://atarihq.com/danb/files/78map.txt is accurate), if desired. This costs some features, but it rocks the 7800 world (IMHO). I didn't think I could get this working, but a little TTL-FU made it work. 
I'll post a pic of the PCB design, when it's done. 
P.S. That is the latest version of BBCC, with the POKEY mapped at $0400. 