I recently built a base for my General 650 as a 'first project' for my
new saw. Instead of building an external steel frame I relied on the
heavy steel cabinet, which is flared at the bottom for extra strength
and instead installed 2 Track-roll roller bearings INSIDE the cabinet.

The roller bearings are 2.5" that I got scrap from EBAY cheap (unused).
They are good for a ton each. I built 2 axels from 1/2" x 2.5" x 21"
aluminum bar, and sandwiched it between 3/4"x2.5"x21" MDF strips. The
result is a solid interior frame with very smooth movement. Just pick
up the saw from the end of the rails, and move it like a wheelbarrow. I
had to make some 1/2" aluminum feet for the side of the cabinet opposite
the wheels to level it as well. I also kept the wheels back from the
left edge of the cabinet, which makes the saw a bit less stable than
normal, so I added a spring type 'foot' which makes if very solid.

Hope you can figure this out.