Hello Ajay,
We are exactly same case as your.
According to SAP ECC 6.0 EHP7 upgrade, you must upgrade first your related system version 7.3 or higher.
EHP7 7.4 only support NetWeaver 7.3 and above.
You can check "Master guide of SAP Enhancement package 7 for SAP ERP 6.0 and SAP NetWeaver 7.4" https://websmp101.sap-ag.de/~sapidb/011000358700000790092013E
Regards.
JS