I'm not sure it's a genuine sportline, didn't they have a different steering wheel? and leather was unusual as the sportline interior was part of an expensive options package.
It just doesn't look like a sportsline (if that makes sense). So few cars that are advertised as sportline are the genuine item - proceed with care if you are thinking of bidding.
As to the sellers comments about the seven seat option costing more to insure - well, that's not true either - well, not in our case and ours is factory fitted.
He's right about the wiring loom (well partly) it's not just steam cleaning that kills it and it should have been replaced by now - many were done by MB under warranty/goodwill but I'm not sure that still applies. I wouldn't knowingly buy a W124 with that loom on it's a very expensive timebomb just waiting to fail.
Other things,
the service history although pretty much complete shows 12000 mile gaps between services - double the recommended on this engine
Not one I'd buy without knowing a lot more about it and seeing the original factory options list
Andy