The calais instrument cluster for VR/VS V6 and V8 are different. I installed a V6 into my V8 before modification with no damage occurring. The only problem experienced was the tacho reading too high.
I converted my tacho to suit a V8 by installing a 220k ohm (220 000 ohm) resistor into the vacant spot marked R3 on the tacho circuit board so that part of the circuit was the same as that of my S pack cluster.
In addition to this, I removed the link in the spot marked R5 and installed it into the spot marked R4. This changes the amount of movement of the needle. (The link looks like a resistor, all white with a single black stripe, but it is not a resistor. It is the same as a piece of wire).
Although I haven't provided pictures, all the positions stated are visable and clearly marked on the tacho circuit board.
I have put a 93 VR V6 calais cluster into my 98 series 3 VS V8 ute and have had no trouble with its operation. The only downside is that the dimmer circuit no longer works., (always on full brightness).
It has been stated that the temp gauge is also different. I have not investigated this due to the reading on the calais cluster being at the 1/4 mark, which is the same as what it was on the S pack dash.