hard drive - Can I incrementally transfer all files in a disk while at the same time changing partition schemes and sizes?

Currently I have an Ext4, 1TB hard drive in a Linux system where personal files are saved. The system files, including home folder, are in another (SSD) drive.

I want to format the SSD to install Windows, but then the Ext4 drive would at best be read-only (of course I am sorry for having chose Ext4 back then..)

Then I got the following idea, but I don't know how dangerous that may be:

1. Make sure to free a lot of space and leave the 1TB disk with at least 40% free space;


2. Use GParted to shrink the Ext4 partition;


3. Use GParted to create a NTFS partition occupying all free space;


4. Mount both partitions and move some folders from Ext4 to NTFS


5. Unmount both, srink Ext4 further, and expand NTFS to catch up with newly freed space;


6. Repeat steps 4 and 5 until every file has been transfered;


7. Delete (now empty) Ext4 partition;


8. Expand NTFS to occupy all available space.

Specifically, I'd like to know about risk of losing some files, or worse, losing all content from a partition or from the whole disk.

Besides that, I'd like to know how I could perform this operation in a safer way, if you think that is more recommended (I don't have spare disks around. I have a paid Dropbox Account, bit still I'd like to spare the weeks I would need to upload everything.