I wasn't going to answer the question with this, but due to the latest comment from the seeker, I figured that some photos will be useful.
So until you get the braze-ons tapped, here is a backup solution (or a permanent if you want) that worked for me. I found that the hardware that came with my rack was too small to thread into my bike, but did fit through the holes. Bolts that thread into my frame didn't fit through the holes in the rack. So what I ended up doing was taking the original bolts with me to the hardware store, rummage through the bins for 2 hex bolts, lock nuts, and lock washers that are the same size, but longer.
I put them on the bike with the nuts on the outside of the frame, but I still had a problem of the bolt head into the chain. My solution was to file off the top of the bolt head until it cleared the chain. It ended up being pretty close to the chain, so if a replacement is wider for some reason, I'll have to file some more. However, this setup has held up well for years, a few thousand miles, and a crash.
(full size image)
This photo (sorry about the dirt) shows the bolt head side of the setup. There is 2 bolts here, one on front for the rack, and the one on the back for the fenders. The shiney here is the fender bolt, but the bolt on the front is even closer to the chain. May not be able to get a piece of paper in there. Yes the chain runs right by it and not over it.
Here is the outside of the frame showing the nuts. Standard lock nuts with the plastic ring in them. The washers are the wavy lock washers and not the split ring ones.
I may update this with better photos later.