Yes. The 645 lenses fit and work on the 645N. Of course they will not AF but the focus confirmation dot works and MF is not a problem with the big and bright viewfinder.
The only (slight) incompatibility is that on the 645N the aperture recording on the film (if enabled) may be off by half a stop.
The 645NII afaik uses the same lens lineup as the 645N.