Considering the high dosage of oxycontin he's taking, 60 mg methadone wouldn't be enough to satisfy his dependency. Even a 100 mcg/h fentanyl patch worn on the skin wouldn't do anything for a user with such a high tolerance.
I mention those doses not as as being equivalent but enough to prevent severe withdrawal.
No methadone clinic will give you more than 40-60mg/day. At least in the past. I hope they've changed their practices to adapt to the prevalence of fentanyl.
But yeah, neither 60mg of methadone nor 100ug/hr patch are equivalent to 1000mg of oxycodone. Not close. But they'll make a dent in the withdrawal, after which you work you way up.
If you're trying to get off opioids, the lowest dose of a substitute opioid that makes the withdrawal feel not totally insufferable is best.