4 ohm vs. 3.2 does not matter so no worries there. Not enough of a mismatch to make a difference, especially factoring in the impedence of the circuit anyway.
Do you own any external cabs? Perhaps a 1x12? To me, putting a good 4ohm speaker in an external cab (or even two parallel 8ohms in a 2x12) is a great way to record and even possibly gig these little beauties, yet still have my handy little home amp.
I'd email Weber and tell them exactly the sound you are after. In 12's, for me it was the 12F150T, but YMMV.
One other thought, you may like ceramic speakers better and not know it. My Weber ceramic Sig8S had no flub and nice bass response in both my '69 VC and '68 Champ, where it now resides - this speaker kills in these amps IMO.