Did you wire the car?
Ive played about with rev counters on mk4's and that was how i did it, the board may even be exactly the same, cant remember now though been a while, but om mk4's the clocks to run off DIS were the rarity, and i compared the rev counters out of a car that was DIS and one that was conventional coil and the rev counters were exactly the same.
Are you in a rush to get it done?