Depending on what gear ratio was installed, you shouldn't have any serious adverse effects.
European 16V's came with a 3.07:1 ring & pinion while the NA versions have a 3.27:1. this just means that the Euro versions have a higher top speend than the NA's. Don't forget, the Euros had 185 bhp. 17 hp more than the NA versions so they could deal with the higher (numerically lower) gearing.
If you're really concerned about what effects the gear change may have, find out what ratio was installed. You'll probably find that this particular car won't be great off the line and may not accelerate as well as stock 16V's (which weren't the best for acceleration anyways) due to the taller gearing, but fuel efficiency (especially on the highway) will be somewhat better.
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