Hello Michael,

Maybe use them with the 60.000 KHz crystals to build a very narrow
crystal filter?

Maybe but most WWVB receivers are more crude. They aren't concerned
about shape factors and stuff, all they want is enough selectivity to
make sure the things sync at night even if in California or Arizona. So
there is usally one crystal as a filter, or two in series for the better
ones.

Regards, Joerg

http://www.analogconsultants.com