I retreived and dusted off the wing center section parts from the wing kit. I also started hunting down the other bulkhead parts from the fuselage kit. I did the basic edge finishing on those.
The drawings locate eight holes that are either enlarged or created for wire run/cable run access through the center section. The spars themselves get four of the holes. Two on each side, symetric about the center line. Two holes are enlarged with the step drill to 5/8". The other two are located via dimensions on the drawing. I used a spring loaded center punch, then a 1/16" drill bit, a #40, a 3/16", and then the step drill bit. Lots of Boe lube helps. The other four holes are in the F704C L&R and F704D L&R. Those holes only need to be enlarged with the step drill.
Center section parts
Edge finishing
Used Step drill to open up holes to 5/8" on the F704D & C
