Component selection - difference between 4027 and 4027N flip flops
The alternative will be fine.

The trailing letters tend to be manufacturer specific, usually identifying the package (e.g. SOIC, DIP, etc.) or other properties like being lead free, or industrial/automotive/military temperature ranges, etc.

An example is the NXP version of the 4027. They have two:


HEF4027BP
HEF4027BT


For them, the 'P' one is the DIP package and the 'T' one is the SOIC package. But according to one of their other datasheets (granted for a different part), they use 'N' to signify a DIP package in America. This is probably where the 'N' comes from in that schematic.