Manfred:
I've had the same clearance problem with CX freewheels. Early ones fit a 12 6 frame and work OK, and later ones (probably for 130 mm) don't. I don't kn ow when the transition occurred, but I believe that America freewheels generally don't fit, and I think that most of the earlier CX ones do.
I had to change out the left side locknut and add spacers to the right side (and redish the wheel) to get the later CX freewheels to work.
The standard NR rear hub locknut thickness is 8 mm. I had obtained a C-Re cord locknut which looked the same as NR but was only 5 mm thick. (Thanks t o Mike Cone, when he owned Bicycle Classics.) You'll have to do something s imilar.
Andrew Gillis
Long Beach, CA USA