I am going to answer this myself somewhat.
I ended up doing this:
• copied Y:\Boot\* to C:\Boot. Some files could not be copied. I expected this, and the next step should take care of it.
• exported system store
bcdedit /export C:\Boot\BCD
• changed Windows Boot Manager location
bcdedit /store C:\Boot\BCD /set {9dea862c-5cdd-4e70-acc1-f32b344d4795} device partition=C:
• changed Windows Memory Tester location
bcdedit /store C:\Boot\BCD /set {b2721d73-1db4-4c62-bf78-c548a880142d} device partition=C:
• changed Windows Legacy OS Loader location
bcdedit /store C:\Boot\BCD /set {466f5a88-0af2-4f76-9038-095b170dc21c} device partition=C:
• updated master boot code
Windows_7_DVD:\BOOT\BOOTSECT /NT60 C: /FORCE
• changed the active partition
DISKPART
select disk 0
select partition 1
active
However, it didn't work anyway. I had to do a repair because "BOOTMGR is missing". I believe I should have also copied bootmgr from Y: to C:, but I'm not sure if that was all I missed.
I'm still curious if this is a really bass-ackwards way of doing this process, and I would very much want to know where I went wrong.
Thanks for all the contributions.