I just bought a really old 2 unit building and need to do a little plumbing to get the water flowing properly. I have a galvanized nipple connecting the supply, into a gate valve, into what looks like brass 90 and nipple. I want to replace it with all 3/4 copper pref with maybe a 1/4 turn valve. What I havent seen before is the attachment at the city pipe to the nipple. How would I change that to get where i need to be. see phote: