Impedance is not so vital, in a solid state amp, so would still work fine, unless you intend using the Ext spkr socket also. I use 2 X 1 X 12 Sessionette's, & have experimented with various speakers, Including 16 Ohm models.
I'd like to swap, a Fender Twin, (2 Ch, Modern version, c/w, 1/4 Power, FX Loop, Etc),Great condition, & recently re valved, for, a 65, Re Issue model, in similar condition. Any takers?
http://www.ebay.co.uk/itm/MESA-BOOGIE-MKV-AMP-HEAD-CASE-MINT-/201035317977?pt=UK_MusicalInstr_Amplifiers_RL&hash=item2ecea382d9 Good luck, If you've not got one yet.