We discussed who was irreplaceable a week or two ago. As good as Lindsey Allen is, Mabrey has emerged as a solid alternative. Not as good at the point as Allen, but smart enough and talented enough to do well.
There is no such replacement for Turner. Westbeld is an excellent high post complement to Turner in the low post, and Boley has begun to do good things from the high post too; but neither is better than average, if even that, as a low post player.
I would go with four around one if Turner can't play. Start Jackie Young and go full time Princeton offense... Ball to the high post. Lots of screens and cutting. Make Boley the first sub, and pick spots to use Nelson in short stints.