I gave serious consideration to having it blanchard ground, but i think I'd lose it when i put the first scratch in the thing! That and cost kept me from getting carried away.
I designed, and had the gussets burned out by one of our vendors at work. It shouldn't surprise you that I modeled up the whole damn table too
Weld your tubes to the underside without the legs and have it Blanchard Ground. Then Weld the legs on.
You accomplish a couple of things. The Surface will be flat. And you will not have holes (Allen Heads, Flat or C'Sink) to catch debris which will lead to scratches.
I have had my Blanchard Ground top for 16 years and there are very few scratches on it. It is never treated as an anvil and anyone who hammers on it gets beat to death with the hammer they are using. Dead Blow hammers are the only hammers allowed near that table.
I wipe it down with WD-40 before every use and if I am welding corners down to the table top I place a very thin sheet of copper or aluminum down to avoid having splatter stick. If I do get any splatter I knock it off with the tip of a file.
Thinking about building a new Table with fixture holes 60 x 120 x 1 inch.
I like that you are using levelers. Makes for a sound foot print and you can level it making the use of a level or protractor and aid in squaring frame structures. Casters are not my thing. If I need to move my Table I welded a couple of cross members 3.5 inches off the floor so I can use a pallet jack I purchased off Craigslist. One crossbar across the back and one set in from the front incase I want to sit down and weld smaller parts. The cross bar is not in the way of my feet or Tig pedal.
Get that puppy ground...you will love it...