Shouldn't think there'd be any problem with the bike, but you don't specify what type of mavic rim and how many spokes. However, you say that you used to race the bike off-road so I'm guessing the wheels took plenty of punishment. If this time around you're initially just riding on paved roads, I'd say you'd be OK.

Ride it. If it turns out that the rear wheel isn't up to the task, you'll need a stronger one. But cross that bridge if and when you come to it.