We had a dish very similar to this in Portugal, except they used rabbit instead of pork. The clams and meat made a wonderful combination and while I was eating it I thought pork would make another good choice. Do try this, I'm sure you'll enjoy it!
If you cook clams this way for 30 to 40 minutes, you won't want to eat them. Clams need only to be cooked until the shells open. A cataplana is a tin-lined copper vessel shaped like a big clam. It is never a cast iron dutch oven.
I dig fresh clams every week, they do not OPEN when "tapped" they close when you touch them. If any don't open AFTER they are cooked, throw them away, because they are dead