You're in for some fun - Im working thru similar set up myself at the moment.
The slicks raise the front by 8mm and the rear by around 12mm over standard tyre sizes. So overall your c of g is now higher and possibly more forwards than previous.
Dropping just the front or trying settings that 'work' for the NSR won't really work. It's not really an NSR anymore.
Work through it methodically to find what works for you.
Do you know if the ZXR forks have changed the offset of the forks / front axle at all?