You should be able to reactivate the old address and use it to open an iCloud account - sign out of the present account and sign in with this address (you will need its original password). You will probably find the the @mac.com version won't work - the @me.com version may and the @icloud.com version should, but you'll need to experiment. Enable Mail etc. in the checklist.
You can then either use this as your account, or sign out and back in with the ID you were using before, then add the ex-MobileMe one in System Preferences>Mail, Contacts and Calendars.