I've got copper pipe under the house that comes out of the exterior walls at two a places. Attached at both of these is a galvanized 3/4" male NPT union that connects to a 3/4" female galvanized tee. Coming out of each tee is a brass hose bib and PCV going to the sprinklers.

The galvanized pieces look very corroded, the threads are starting to slowly leak and I want to replace them and redo the PVC going to the sprinklers. Do I use a brass union & tee to replace the galvanized parts that connected the copper to the PVC?