The belly dish is most likely a redcooked pork belly, then given a roast or deep fry to render more fat and crisp it up. It's an excellent dish and red cooked dishes deserve a lot more attention than they get. Shoulder could be treated this way too, particularly with the skin on if you want crisp skin. I'm a big fan of red cooked chicken wings too.
The pork shoulder is often used to make various roast pork dishes and would be a good choice. You can find it both skin on and skin off. I've never found pork skin to my liking so if you want crackly pork skin, I don't have a lot to offer for advice there, just what I've read.
Of course you can make pretty good char siu with strips cut from the pork shoulder as well. Lots of recipes recommend leaner cuts, but the result isn't as moist as from the shoulder.
Red cooking is best if you can devote some freezer space to a gallon of broth that you'll reuse over the years. Of course, you can mix up a batch of broth and then discard it afterwards, but they get better with use. And there are some shortcut broths that get used too for things like soy sauce chicken.
Tell us more about what you're wanting to do, and what cuts interest you for doing it.
http://books.google.com/books?id=eIIrRUHGJawC&pg=PA148&lpg=PA148&dq=chilled+red-cooked+beef&source=bl&ots=F3_c2AQXuC&sig=DjVtCAPERca4EIJ7xvIEvWSmCzM&hl=en&sa=X&ei=8BQoUMy1K7SGiQLPk4CwDA&ved=0CDkQ6AEwAQ#v=onepage&q=chilled%20red-cooked%20beef&f=false Scroll down that linked book page and you'll see my favorite red-cooked broth base. The only thing I'd change is to reduce the star anise some.
Darn, that link keeps jumping to chicken even though it says beef. I'll work on gettin the link to work right.