Not long ago when M posted Star Wars Begins to usenet
first thing I did was to download the last RAR (part090) and extract the CRC from its header
because I wanted to check it against the disc JD sent me. It didn't match :(
So does that mean M is a . . . F-word? No, no, no!
Here's a hexadecimal dump from M's image file:

The highlighted parts are the mastering date.
With punctuation added, it's 2011-02-02 19:47:14 in JD's local time zone.
This disc JD sent me contains exactly the same VIDEO_TS files (I made sure of that) but mine was mastered the day before, or the day after I can't remember, so the ISO image is not exactly the same.
Even in this ''best case" scenario (presumably JD used the same software both days) re-creating the image would require to guess the mastering time with a precision to the nearest second. In the worst case, without knowing which software originally made the torrented image, synthesizing it becomes next to impossible.
Now having said that, this project sounds like a lot of fun. Count me in.
I see ten or more on walkingdork's "currently leeching" list that I can probably seed. Some of those were seeded as image files, but in those cases I would have saved the first few sectors from the original image and the last few sectors -- enough to reassemble the image without any guessing.