Kawasaki K750 B twin blocked

Hello
Its been a long time i was not here but currently i bought new baby which is Kawasaki Z750 b twin 1982. It is not yet ready for ride but i ready in papers that engine is blocked to 20kW.  This is carb German version. How to restore full power? There is nothing in carbs that could visibly could lower the power. Maybe jets?
Please help because I do not know where to looking for.
Piotr

Longer vaccum carb slider, restricted rubber carb boot ports, restricted
exhaust header (welded washer) and low lift cam shafts will do reducing gas flow and hp.

www.z750twin.de/schnittmotor.htm