A couple of thoughts spring to mind, Currently my own Myford S7 clone sits on a clone cabinet, but essentially all similar to original.
As a temporary measure when I moved in to the new house, where the garage floor is uneven, I use 4 adjustable height feet; essentially lengths of threaded rod, with a ball end plugged into a disk of nylon. They are plenty strong enough and easily allow adjustment for the uneven floor; I'd have struggled with lengths of box section, as I'd have still needed lots of bits of packing.
The advantages; ease of adjustment, quick, cheap, allows some storage underneath in old baking trays, adds enough height to save me bending over too far, makes it easy to move the lathe away from the wall, for access to motor etc.
Disadvantages; if something is out of balance, the whole assembly is more prone to vibration, a real pain finding stuff underneath when you've dropped it, arguably less stable, but I can't imagine it toppling forwards, and there's a wall behind it.
In my old house I had a washing machine in the outside toilet, again on an uneven surface. Eventually I added a couple of heavy 3'x2' concrete paving slabs on a layer of mortar. This allowed easy levelling of the slabs before the mortar set. maybe replace your old work surface with a pair of these. They are the 40mm plain concrete paving slabs, not the lightweight ones for garden paths. They are also heavy enough that you could bolt the cabinet to them, without drilling the floor.
Bill
Edited By peak4 on 06/11/2019 12:38:00