Low wattage amp needs another spkr

I have one of Paul Sanders' Nolatone amps, a 15 watt Rotten Johnny, 112 combo w/Reaper 30. I'll be adding an extention cab  speaker (open/closed convertible). What would pair nicely to give this rig some rockin' punch?  The Reaper is a great all-around, well-balanced speaker. I'm happy with it, but I'd like some punchy thump too. I play mostly humbuckers (if that makes any difference).  Thanks folks!

-BILL

If it were me ... it would be a Retro 30 ... or if ONLY paired with the Reaper, an ET65.