The casters lift one end of the stand a bit, so it won't drag on the floor. To keep the stand level, it follows that the other end should be lifted the same amount. I used a piece of maple, 22 mm thick.

The foot pads are supported by the legs, but also need support on the inner corners, so they won't tend to tip up.

Here's how the brace nestles into the inside of the leg.

Some glue plus two screws hold each pad in place.

The brace is trimmed so waste landing on top will slide off.

The casters are mounted on a nice piece of birch. This is, in effect, a subassembly that will keep the casters aligned with each other.

Two short pieces of oak, trimmed to match the angle of the legs, support the subassembly inside the legs.

I set the legs on a board the same thickness as the foot pads. Then, I held the subassembly in position, making sure that the top was level. Finally, I clamped the supports to the inside of the legs. While the clamps were in place, I drilled holes for carriage bolts, thus assuring correct positioning of the supports.

Finally, I cut two more support pieces to fit between the other side of the subassembly and cross pieces on the frame. All four supports were “screwed and glued” in place. There's nothing holding the top of the supports to the cross pieces, except gravity.

The socket is mounted at a slight angle, matching that of the legs.

Right side up, you can see the way the board is tilted to match the legs.

Finally, the board was clamped in position and holes were drilled for carriage bolts. The height is such that the dolly's ball will just barely slide past the rim of the socket when the dolly's handle is vertical. When the handle is lowered, the dolly lifts the end of the saw.

I slid the original rubber feet over the ends of the legs to cover the the sharp corners. They're clear of the floor, which is just as well, as they used to stain the vinyl floor tiles.