A lot of people will view this process as barbaric. I did not have anything beyond gravity holding the frame sections down to the floor. I considered buying 3/8" x 4' x 8' sheets and welding the legs positioning the frame sections to the sheeting. I was quoted a price of $370 a sheet for the steel, and would need 5 sheets. At that point I might as well buy a prefabricated frame fixture table.
I marked the locations of the legs on the floor using a sharpie to ensure that I had not moved anything around to a different part of the garage floor, as I leveled and positioned the frames in that location and the floor is not level across its surface.
That being said, the heat from welding did pull on the frame, causing some slight bowing upward of the rails. This distortion may have been minimized by welding the legs to plate or attachment to a fixture table. The distortion was nearly equal from the left side to the right side, and was equal to .125 to .1875 of an inch. Some will gasp at this result, but I am not building the space shuttle. Typically, automotive collision repair of unibody cars mandate that the dimensions between reference points on structural members be within 3mm to constitute an adequate repair. This is equal to .118 inches. Do your best to keep things within an 1/8th of an inch.