Thanks, I never knew a laptop hard drive was so easy to remove. Utilizing it as an external drive (cost under $10 for the enclosure) is something I never considered. Your advice, while not specific to my original question, was very much appreciated.
There are variations on SATA to USB/FW adapters. Some are barebones without a case for the drive, like this one:
USB 3.0 to SATA Adapter Cable - UASP-enabled | HDD Adapters | StarTech.com
However, the drive removal process for those MacBook models is ridiculously easy, and Apple considers it to be a DIY job with published instructions publicly available from Apple:
The only thing they don't have in the instructions are the tools needed - either #0 or #00 Phillips screwdriver for the "RAM door", and a T-8 Torx screwdriver/bit to remove (and possibly reinstall) the drive "sled". It usually won't fit in a drive enclosure with the sled still attached, although it won't matter with a barebones adapter that just plugs in. So you had all the tools you needed to do this?