Preserving a whatsapp account from an inactive/foriegn SIM on a new device
Just take a backup of the WhatsApp conversations in old phone and copy the entire folder /sdcard/WhatsApp/ and send (copy) it exactly to the same location in your new phone..

Now open WhatsApp from new phone and Enter the desired number (It may or may not require verification)
After verification is over, it'll prompt you asking for restoring chat backups..
Just restore them.

The latest version of WhatsApp supports backing up of data to Google Drive.
So, if you can update to a latest version, better sync it and try the same.