Without being there to measure you might be able to move up to a -5 or 5/16" rivet,
All of the dimples in these picture look really bad to me. It may be just the lighting or the angle, but several others look deformed, or not formed correctly. What are the scratches from? What type dimpler are you using?
Personally, I would abandon it and drill two new holes on either side (assuming edge distance allows) and add a doubler behind the spar. File the hole clean so a crack cannot propogate. Later the hole can be filled.
Ask Vans for an official opinion.
I believe you mean a -5 or 5/32" rivet.