Gogogadget said:

If I did the '81 crawl with the incorrect musical cue, you'd have extra frames and then the audio would have to be re-synced to the entire movie.

Aren't the lengths of the '77 and '81 crawl/flyovers the same (the frames are different internally, but they start and stop at the same place)? So if you pasted over the '81 crawl/flyover with the existing audio, the audio glitch would "just happen" exactly correctly?

EDIT: Harmy beat me to it. And yes, the framecounts are different if you just do the crawl, but you'll find you have to do the whole crawl/flyover to do it right, and then they line up nicely.