Fixing a Windows partition boot using OS X tools
I'll post this as an answer, even though it didn't fix my problem – this was a lost case in the end. Aftermath: I dd'ed a backup of the Windows partition to my OS X partition:

sudo dd bs=512 if=/dev/disk0 of=windows_backup skip=732993496 count=173955112


Now I had a 80 gig hex dump which I could examine safely. I used a hex editor to search for all kinds of metadata:


"NTFS" (encoded in ASCII) which starts a NTFS volume.
"FILE" (encoded in ASCII) which starts a file entry record in the $MFT or master file table in NTFS.
NTFS system file names (like "MFT", tried with little-endian UTF-16 and ASCII)


... and so on. But without success. I was able to find all kinds of data from the dump, but all the metadata, including the boot record (the first sector of the volume), the $Boot file (the first 15 sectors after the boot record), the $MFT file which keeps record of all the files on the file system, were gone.

The thing that baffles me that I couldn't even find $MFTMirr file, which is the backup file of the metadata files and stored halfway of the volume.

I was able to find a backup of the boot sector from its standard location, the last sector of the volume. However, the data was old, from the era before resizing the volume. The boot sector has stored the offset of the $MFT file metadata file, but inspecting the references was moot, there was nothing of value there.

In the end, I concluded that the volume was totally borked. The moral of the story? Hybrid Master Boot Record is evil. Also, it seems that the program that resized the volume did a subpar job, failing to update some of the metadata.