IMHO go with a fEARful 15/6 flat pack. The stock 8 Ohm 3015LF is tonally different than the 4 Ohm 3015LF-B that Avatar uses. The 4 Ohm driver gives up in the lows to meet impedance requirements.
The 8 ohm version is available again at Avatar:
http://www.avatarspeakers.com/TB153.htm