Since I posted last: Purchased one new rim and two new 28/11 Ag tires; painted the rims and hubs and filled the tires with windshield fluid. Rebuilt the axles with new seals and today reinstalled the brakes.
I think I have it right but I'm posting a picture of the left side, which has the extra "helper" spring. In the picture it is the smaller of the two on the left. Let me know if it is in the wrong place.
There isn't a lot of "how to" for 8N brakes. Maybe I'll pass along what I learned.