I have build (and am still building) Pi7´s for my HT room in the basement.
I use the Eminence Delta 10 for the midhorn, and have substituted the HF driver with the Altec 902, which sounds alot better than the Eminence PSD-2002, to me that is
For the bassbin I got some old JBL 2225H´s that had lived their lives in a PA system. These drivers can be had cheap and are still very very nice bass drivers.If you got the money go the JBL way, you will not be disappointed, and if you don´t like them, you can always get good cash for JBL drivers.