Well, you have to run a new cable to the eDis module - don't use an existing one. The converted rev counter has it's own wire.
I looked at some photo's and noticed the 1.2 RN had a rev counter. I think it was standard but not 100%.
The Mk1, Phase3 RN had the 1.2 DIET engine too, so, my guess, is those dials are more likely to work out of the box than any other.
I'd definetly be trying RN dials - beecause getting rev counter converted, running cable, etc.. is far more hassle.