OK, ready to rivet skin on hs....nose ribs done, spar in place, skin clecoed to spar and main ribs. Rivet call out for skin to spar is -4.......I placed a -4 rivet in and it looked long, marked it and measured .162. 1.5 diameter is .141 for a -3 rivet. FAA guide has a 1.33 min. Diameter to 1.5 diameter of the shaft for pre driven rivet. The -3.5 rivets looked right, and I think it measured + or - the .141. ? Should I go ahead with the 3.5's or do I do more investigating? Thank you for your thoughts.