If I normally roast shoulder of pork at 160c and this time I wanted to do it MUCH slower cod I Cook it at 80 celcius for 100 mins per kg. This would bE after doing it at 220 for UHF first half hour. (it is a 1.2 kg roast shoulder)
I cooked a 2kg shoulder for 30 mins at 220c and then 4 and half hours at 170c, wrapped tightly in foil. 80c, I think would be too low. I looked for Delia's recipe on line for you but no luck. Happy cooking