Twisted pair for long distance voltage measurement
Common mode voltage (DC and noise on whatever it turns out to be) is likely to be your biggest problem. A shunt is a very low impedance source and is easily filtered if you don't need fast response. You don't need a twisted pair in that case, though it won't hurt. 

If you filter the shunt voltage well at the ADC end and use a differential amplifier with a bipolar supply (such as an instrumentation amplifier) to amplify the voltage up into the ADC range you should be okay. 

If you're planning on going directly into an ADC with an on-board PGA and unipolar supply, I think you're going to have serious problems.