If you want to use the stock speedo your going to have to get a converter box from the tranny. The tranny has an electric signal to the gauges, and the stocks are mechanical.
The tach you run off of the standalone harness with a resistor to get it to function right.
The water temp / oil pressure gauges are run off of the stock sending units from the L6.
For the oil just get a t-fitting and toss the sending unit on there.
The water temp is the same in the side of the block between 2,4 cylinders.
As far as the clutch master I went with a willwood 7/8'ths, I'm not running the t56 though.