The surface plate and v-blocks will do the trick as long as the v-blocks are not homemade trurds or have been beat on like Ike beat Tina.
With regard on what you can touch off, it's basically got to be a pin. However if you have some v-style feeler gauges, you could swipe one from the set and solder it to the removable portion of the stylus on the dial indicator. I know its a bit of scince project to make a tool, but if your pins don't have centers drilled in the ends of them, then you don't have much choice.
.................oh yeah, and what do you mean you don't make splitting your cases an everyday occurence? I thought everyone was like BigRed and simply used it as an excuse to drink beer. :biggrin: