Here is an updated pic. I threw together a wood frame to hold my curbside find

I had wanted to weld some legs on it but I had to rethink that plan after pricing 2" angle steel
Nice score . . . . that has lots of possibilities.
I'd keep designing / thinking on your legs as I envision some removable legs that are adjustable up and down. Like an output table for tablesaw / router so you could cut long stock.
IDEA:
Could use square pipe (steel or aluminum) as legs with larger attached (maybe 16 inches long) then a smaller square pipe (say 15 inches long) that slides up into larger pipe. At bottom of larger pipe, there'd be hole drilled and nut welded on so "Stop" bolt could be tightened or loosened. Repeat on all 4 legs. On one end (or both) could even make the legs removeable from base with a pin or bolt (ie square leg fit inside yet a larger square pipe).
Just the bottom of the smaller slide-in legs would need feet welded on.