Hi Radhesh,
You have 2 options.
1. Update Gateway to 740. I guess Gateway is not productive use. Your basis can install 740 without any risk.
2. Use Embedded deployment on ERP. ERP is already 740. It means ERP has Gateway and UI add-on component. You can install UIX01HCM on ERP.
Regards, Masa
SAP Customer Experience Group - CEG