Thanks for that pic!
But the bike's too high for sidecar racing, IMO. In the past, when the Moto GP class still allowed sidecars, those always were as low as possible. Low engines like the flat twin BMW were popular:

More modern, with a 4-in-line Fireblade engine:
Also, using a 250 or 300cc ETZ engine for that seems a poor choice - 40hp for 2 big boys? A tuned Fireblade will be in the 230hp range, I'd guess. While that's not very 'classic', also in the classic range there should be better engine choices for sidecar racing.
Anyway, to each his own, and surely this is a classic MZ 2T so thanks go once again to breakwellmz for showing this interesting pic.
As an MX rider I detest sidecars, as they used to ruin the track. And on a deeper level, that sidecar takes away an IMO very important aspect of bike riding: the balancing of the bike in the corner! It'll ride more like a car.