I'd add Henshaw to that at the moment. McCloskey is there but we don't know what he can do against the world's best sides yet. With Henshaw and Murray we're a match for anyone right now.
Marshall would be a safer bet than McCloskey right now. Also, Ringrose and Payne work just fine, although obviously less so with Payne injured. And of course there is always the mighty Noel Reid waiting for his shot.
edit: That said, Henshaw belongs in the tier just under of people whose absence would bloody well sting, along with Best, Sexton and Furlong.