Nice Cab Paul! That looks great and I like how you documented everything with pics!
I am no woodworking master and I got the cab kit from mameroom (though I received some broken pieces will see how they replace it

)
I'm going to see if 1x4s will do the job on the bottom with castors. I don't know how to modify things that well as I am definately no carpenter and don't have the resources to have built my own like you did Paul...though it does look awesome!
Thanks for the link Shmokes!
That does give me different options to think about

It's just with the mame cabs the weight really is completely supported by the bottom sides of the cabinet...the base is just to support the sides a little and istn;t even touching the ground...but certainly not a support piece.
I'm thinking of just haveing the 1x4's placed perpendicular to the sides on the bottom (having the cabinet lay on the 1x4s as if it were a pallet) with castors.
Hope this works....but still considering other options .... totall work in progress!