So, I got this idea and I'm going to try it this weekend. Hopefully it sounds good and not like crap.

But I'm going to run my guitar > tuner > Boss NS50 > A/B box

Then from the A/b box into both my Peavey Ultra Plus and into my Mesa Duel Rec.

I'm going to run both effects loops back into the NS50.

Then I'm going to use my old Carvin cab that is stereo. The top left and bottom right are Celestion GK75s which will handle my Peavey. The top right and bottom left speakers are Vintage 30s which will handle my Mesa.