What is the equivalent amt of morphime one would need to take day if they r switching from 120mg methadone daily?

It varies by person. Equvalencies when switching from Methadone are tricky. At low doses it is 3:1 so 120 would equal 360. At higher doses of Methadone and with more chronic use- some say that the equivalence can be as much as 10:1 (1200mg) however, there is no such thing as perfect cross tolerance and a starting dose of another opioid should be less than half the equivalent dose followed by quick adjustments.
Start slow. Theslows he initial answer is correct. There is no textbook answer. Methadone is especially tricky to switch from. A good starting point would be in the 20-30 mg per day range and then titrate up slowly.
Titration. People vary so greatly that i don't giving patients schedules for switching. It depends on so many factors like, underlying diagnosis, frequency and duration of pain, individual tolerances and history or prior medication responses. Your doc needs to start low and go slow! you can always give more but can't take away once given. Start 1:1 then titrate. What works for one, doesn't for another.
1440 mg. The "morphine equivalent dose" for Methadone is complex and escalates with higher doses. Above 60 mg per day of methadone, the conversion factor is 1:12 so that 1 mg of Methadone is equivalent to 12 mg of morphine. See dose calculator at http://www.Agencymeddirectors.Wa.Gov/.