Few hours remeasuring every thing on the wing to find why it was out of square by an inch. After measuring the LH wing I found my mistake: I measured the ribs off of the inboard spar from the inside of the fat rib rather than the outside where the fat and skinny ribs are identical. Ended up drilling out 5 rivets and moving the ribs over about 1/2", added a filler rivet to fill in the vacant holes, and marched on. Still not dead on square but it is as close as I could get it. All main ribs are now riveted in place at leading and trailing edges, as well as along the main spar. Cross brace also installed and riveted in to place. Next step will be upper and lower false ribs.