Yes you are correct. Here's a summary of what you should do, in order to migrate your OPC interface:
1. Install OPC Interface on new machine (already done in your case)
2. Copy Old Bat File Over to PIPC\Interfaces\OPCInt directory.
3. Create new instance from this Bat file.
4. Configure Interface identical to old interface
5. Configure DCOM. (Check with PI-OPC Tool to connect to the OPC server)
6. Create trusts on PI Server.