In terms of lug brazing, brass is a whole heck of a lot harder to nail than silver. I like to braze everything w/brass, even stainless, but in our class we teach w/silver because new folks have a much better time with it.
If you go with the brass, get 1/16" bare rod, low fuming. Scotch bright the rod to clean, and heat/dip it into powder flux as you go, as well as cover the joint in paste flux. Allstate 1113 paste flux is killer stuff, a bit more temp range than the Gasflux, and cleans easier.