Lemina has to play, Romeu should play, Austin and Boufal have to play and defence and GK is settled.
So it's basically two from PEH, Davis, JWP, Tadic and Redmond.
Redmond makes sense against Arsenal as we need to press them aggressively and get in their faces. I'd go with Redmond and Davis.
4231 with Romeu and Lemina holding, Davis in front, Redmond right and Boufal left.