IMO, the display tank needs to be fallow for 76 days to eradicate Ich. During this time, I would not add anything wet that has not been quarantined (e.g. corals, snails,..). If you do, you are taking a risk.
What treatment are you planning on using in the quarantine? If using copper, I would recommend Copper Power. It is a chelated copper, which seems to be easier on the fish. Also, do not dose the entire amount at one time. You want to bring it up to therapeutic level over 72 hours if possible. Be careful with ammonia levels in the quarantine as well. Best of luck.