Richfilth

Ive just picked up a clean '82 Coupe here in Poland and, although the body is mint, the interior wiring loom is a mess, from the previous owner's love of stereos. Im trying to work out how to re-install the VDO gauges, and my own stereo but, short of taking it to a pro stereo shop, I have no idea what wires feed into the gauges.
Can anyone give me a hint as to what I should be looking for? Original wire colours to the oil, voltage and pressure readings, or average read-outs on the wires for the appropriate cables?