Yep, the CBR is a miserable 4T and has less power than something that doesn't have a lot of power. Great bike though if you like that sort of thing.

So anyway, the upshot of the initial question is no, the heads won't bolt on, but the cylinders share the same stud pattern, so will fit the cases.

Remember, that up until the NX5 was released in '93, the NF5 was always just a race developed version of the MC16. Many "sort of" interchangable parts.

For the record, I believe Yamaha went the other way, in that the racer was good so they built a street bike to similar (detuned) spec.