Ty,
Of course it is a VECO or DUMAS die-crush from a Bob Palmer design - Smoothie, Chief, Warrior, Brave, etc.
The "dirtee comeek boook" plans that came with those showed what to do with those round holes at 60% chord. There were these 1/8 square strips in the kit box, remember? Shove them through the holes in the ribs, and they came to a sort of agreement about a shape between round and square, and acted as aft auxiliary spars.
That was sort of a Bob Palmer hallmark.
I did that, because the plans showed and described doing it. It still makes sense - some added stiffness at near no added weight.