the nsu were the bikes of world records and championships. this history is credibility from the day. the sportmax and super max 250, as cool as can be for the day, but are painfully slow of the speed we now expect. the weight is great and the brakes are little more than a hope better than the drag of engine. but the style and legacy are worth these things inadequate. the races you will not win. but the quality is of the art of the day.
Without knowing the model you have its impossible to comment. If its a Max or SuperMax you can have a bit of fun with it. AirTech make replica fairing, tank and seat so you can make it look like aa SportMax. A long time friend in Ireland has a SportMax. The real deal. Not a replica.
P.S. If it looks like this one. Give me a shout. I got great idea for it.