So - it's just for temporary installation of windows (messing around). Am I understanding this correctly?
34GB would be enough for initial installation. But it will fill up quickly. And when next big windows update gets released, you won't be able to normally install it. I'd say 100GB is probably minimum for normal operation.
If you want to make 500GB disk bootable, then perform these commands:
diskpart
list disk
select disk 1
(make sure 500GB disk is selected)
list partition
select partition 3
(make sure 34GB partition is selected)
shrink desired=500
create partition efi
format fs=fat32
assign letter=H
exit
bcdboot C:\windows /s H:
bcdboot command will create bootloader files on 500GB drive and will add bootloader entry to 930GB OS partition.
Next - disconnect 930GB disk and install windows onto 500GB disk. Specify 34GB partition as target for OS installation.