RV-8 HS-405 and section DD

[WA85]

I am encountering the infamous HS 405 and section DD confusion.
There are many dimensions given in section DD and I am somewhat confused as to which ones apply to the simple task of marking and drilling the holes for the forward flange holes of HS 405 to the HS 702 spar. HS 404 has a small flange and it looks like only two rivets can be installed through it, the front spar HS 702 and into HS 405. Are these the only rivets that will attach HS 405 to HS 702 and HS 404? Any pictures of front HS 405 riveting would be appreciated.
I am probably over thinking this, but I hate drill before I know for sure where.