Isnt it easier to find a pair of fronts with 3-6 dB higher sensitivity & 8 ohm impedence??
First of all few speakers are 8 ohm, even if the manufacturer says they are. If there is more than one woofer, you can be pretty certain it is four ohm, even if the rating is the spurious 8 ohm nominal.
Next you choose speakers for sound, and not based on impedance and sensitivity.
Choose your speakers and then power them accordingly.