change to senoir apartments?

I live in Illinois and I will be closing on a 3 unit building early August. One unit is currently empty and I have the right to show it with the unit becoming available when I close. The present tenants are both single senior women who take very good care of their places. Is it possible to make my building 55 and over, only? And while I’m at it. Can I go for a non-smoking property. too?