They both have the exact same hardware, so, you should be able to download the stock firmware for SM N976B and flash it on the SM N976N using Odin without issues.
On the SM N976N device, go to system settings>about>software information>build number. Look at the build number and find the 5th character from the right, this is the currently installed binary version.
Then, when you find the firmware files that are available for the SM N976B, look at thier build number and make sure that the 5th character from the right(the binary version) in the build number is equal to or higher than the binary version of the firmware build number that is currently installed on your SM N976N device. Do not try to use a firmware that has a binary version that is lower than your current binary version, it will not work.