joe kilo,
I like the construction of your table base design so far. Simple and beefy.
One thing you may want to consider, is before it gets too heavy flip it on one end, drill a 4" deep hole in the center of each leg, and install a large flange T-nut or brass threaded insert in each hole for adjustable feet. This allows leveling the table for squareness on any part of the shop floor that you move it to. You may not need to use it, but it's much easier to provide for it now in case you need to use them later.
You can buy the feet or make them from all-thread rod, nut, and large washer. Tack weld the nut and washer to the all-thread rod with the washer at the bottom. Or use 3/16" or 1/4" steel plate squares and thread a hole in the center for the all-thread then tack weld it to the all-thread rod.
CarveOne
CarveOne
http://www.carveonecncwoodcraft.com