Windows: Deleted 600GB partition (right side) from 3TB Dynamic disk, now entire drive is unallocated

I have an HGST Enterprise 3TB disk with two partitions: 2TB and, on the right, 600 GB.
The disk was configured as Dynamic (yellow in Windows Disk Management).
After deleting the 600GB partition, the entire disk now shows as unallocated, and all data appears lost.
I’ve only run TestDisk’s “Analyze” so far.

What recovery steps would you recommend next?
Thanks!

Images:

Current Disk Layout/Disk Management
Current Disk Layout/Disk Management

Test Disk result
Test Disk result