I'd do the x-pattern and wire the cab series-parallel 8ohm mono,,,,,,,but that is because I have no need for stereo, and it's much simpler since you don't need anything more than the wire and a good mono jack. Plus all my other cabs are 8ohms, so it makes combining cabs still a perfect match for the amps.
Everyone's situation is different though. Nothing wrong at all about leaving it stereo.
I assume you mean lynchbacks/m65 combo.