It depends on how you’re going to serve it. If with sides, then approximately 150-200 g (5-7 oz/0.3-0.5 lb) should be enough. In this case you will need about 230 g (8 oz/0.5 lb) of uncooked pork per person.
But if it is the main dish, consider increasing portions to 250-300 g (9-10 oz/0.5-0.6 lb). That means you will need about 400 g (14 oz/0.9 lb) of uncooked meat per person.
Pork is high in fat and protein, making it very satiating, so you will probably won’t need a lot. But it’s always better to have leftovers than leave people hungry.