Fell or felly-trail shoes (Wave Harriers)? From memory of the area it's not going to be too rough, and it will be dry. Long run, with a bit of track. I'm sure both would be fine. Which is making the decision even harder.
So you get to decide. Either that or it's one of each.
Wave Harriers for sure. I did a 40 miler at the start of the year in roughly the same area in fell shoes and it was painful by the end of it. It's mostly large gravelly/rocky paths. It's a bit boggy over to Carn Pica, but you'll want something comfy for the rest it.