Using what you have will be fine. Just make sure you clean the brass, as it has residual surface lead on it. It is a very small amount, but cleaning it off would be best. Maybe I should have elaborated on "eventually." By eventually, I mean in a few months to a year. When you couple stainless and brass together, oxidation of the brass takes place at a higher rate. If you do use the brass, you need to make sure that it is not turning green before each use. If it is, the copper is dissolving, exposing more lead to the surface.
"I fear the man who drinks water and so remembers this morning what the rest of us said last night."