It depends how we use him really, he doesn't have to play with another out and out striker, but he does need a presence close to him, someone who can be the battering ram and hold the ball up, which is basically Cahill's role in the side.
With Cahilll away I'd stick Rodwell in that position, personally. Not like he played against West Ham, but right up there, almost as a second striker. Similar to how players like Gerrard and Diaby play in that role.
I have a feeling the Bilyaletdinov-Beckford combination would be a little lightweight, and the ball would just end up coming back at us. Bilyaletdinov struggles to shield the ball against fullbacks, I'm not sure how he'd do against six foot plus centre backs and physical defensive midfielders. Although saying that, I have no idea how he'd perform the role. Some players really come into there own in more natural surroundings, Osman for example.
Yakubu-Pienaar would be an interesting one.