I’ve been scouring the eBay “broken or for parts” section to snag a decent MacBook Pro that doesn’t have a hard drive and/or working display.
If anyone would like to contribute, I won’t say no. I’m going to get the least expensive option I can find either way.

This thing will get done, one way or another. The current state of the audio streams is preserved in a master file output, and restoring my system to new hardware will let me pick up from there, even if I potentially no longer have access to FCP7. (It just might be balls to work with audio on any future changes to make.)