Hi,
So, not all the commands are the same between the 2 platforms because one uses classic IOS and the other one Nexus-OS. So, the best way to do this is to copy a portion of the running config from the old switch into a notepad or notepad ++ (it is free), make the changes you need to make and than copy into the Nexus switch.
There is also a tool here for converting commands from IOS to Nexus OS.
https://www.cisco.com/c/en/us/support/web/tools-catalog.html
HTH