I tend to look at things in the light of simplicity and I realize I am coming from a little home studio perspective but it seems logical to do some digital transforms from a classic setup that *will* run the original sessions.
You choose the number of channels you wish to import based on the original session's format.. such as keeping the voice tracks separate from the music tracks, obviously, but that way, all your automation and plugins will maintain their original intent.
It may be a whole lot cheaper to rent an older HD system with the appropriate plugins for a one time conversion than it is to surgically translate between the versions.
And while you are at this, catalog all the original audio files so you can easily find the tracks you want for your surround efforts.
If my quess is right, you could easily find a studio willing to do the busy-work once you've decided what format/form you want the conversion done.
Then again, maybe Digi has already contracted with some of the bigger buck studios to do exactly what you need and all you have to do is pay them the big bucks for the converter
How extensive was your plugin selection for the early shows?