Seeking Advice on Making a Rotary 4th Axis

I `m planning on making a rotary 4th axis for my CNC mill and have a
few questions: I already have the servo and drive so that isn't in
question. I was trying to decide if I should start with a rotary table
or perhaps an indexing head or super spacer. I know that the ratio of
the turn handle on a rotary table provides more accuracy and torque
being in the 40:1 range as apposed to the 25:1 ratio of an indexing
head. But what I am most concerned with is the back lash and the
holding ability. I'd like to use a 6 or 8 inch table so I can mount a
good sized chuck to it. I was wondering what people here have done
like this? And if any one has any links that they might think useful,
I'd appreciate that too.

Thanks

Peter-