You've got some decisions to make, Lou.
Correct times and temperatures should be based on your expected outcome for that piece of meat and bone, not some strangers.
As Ember recommended use the use the 55°C for 8 hours if you like your meat pink with a great chewing experience.
I prefer a braised Lamb Shoulder cooked long with a very moist and tender result. I would cook one that size for at least 24 hours, 36 wouldn't be too long for some lamb depending on age and heritage. Be prepared to deal with a lot of fat and bone, not much meat.