Doesn't matter how long you would braise a belly, it won't keep the great texture and will just be tasteless. To preserve the real taste of it and add some extra plus keep it at maximum of its tenderness, just CONFIT it.
Heres how: [i made the dish, we sell it in the bar]
First i take the skin off the belly - if you have whole, i would cut it in half, then press skin side down and by using thin flexible knife i cut the skin out by pressing the knife lightly and do as many strokes as it would require. You will be left with smooth surfae and great presentation later.
Second step is marinating, and i believe in simple yet real flavours, so i use only garlic onion thyme and rosemary.
Leave the thyme as it is, pick the rosemary off the sprigs, but no chop, the garlic cut in slices, not too small - similar with onions. Will be easier to pick it up afterwards
I put little oil on cling film, herbs, belly, herbs and i roll it with cling film.
I leave it for 24-48 hours.
Then its time for confit. Oven on 180° C, oil into deep pan/pot. I heat it up until i reach 170C.
Then i pour it over to tray where bellies are, i clean all of the herbs and spices off it, herbs tend to burn in that temperature over long period.
The oil should cover the belly fully. Then I cover tray and stick it in the oven. Depending on the size i would allow 90 to 120 minutes.
When pierced by knife should make feel like soft butter.
Then i cool it down, then cut portions, and then when order comes i use red hot pan, no oil, just stick piece of belly fat side down, throw in spring of rosemary and off it goes to oven for reheating.
What you dont use, you just store in the oil - thats the whole idea of confit, isnt it?

Dont be affraid of the meat to fatty or lazy flavour, it wont be
Enjoy