Here is one of the more recent threads that has a lot of info.
Rather than repeat, look at my posted #18.
As for reaming all of your holes #30... if a rivet will slip into the holes in the skins or ribs individually, then you have a hole alignment issue as described in the other thread.
If not, then reaming might be the way to go.
For a strong rivet joint, a close fit of the rivet to the hole is required, because the rivets done swell in diam. as much as solid rivets.
Solid flush rivets fit into the holes easily because when the holes are dimpled, the hole diameter actually gets larger.