It never got warm enough to varnish the roof ribs. Maybe it will this weekend. I did do some more fitting of the ribs to the rest of the roof wood, and I added some shims to get their height correct. I also checked the fit of the wooden blocks that the sun visors mount to, which go between two of the ribs.
For the door latches, I got some special stepped rivets from a parts vendor, but they turned out to be not quite the right size. I guess I will try making some.