Hardware compatible with FCP 7

A project we began 8 years ago was set up in Final Cut Pro 7. Our editor prefers that version of FCP and does not want to migrate to a more current version.

We would like to move a copy of the project files to a second laptop so we can assist in editing and still be able to transfer segments back and forth AND retain the ability for all parties to edit. We understand that bringing any of the files into Premier for editing will make it impossible to send the information back to FCP7 for further editing.

At long last - our question. What MacBook do you recommend and what are the minimum specs for hardware that can load the most recent OS that can still run FCP7?. Can this be accomplished with a new laptop OR are we better off getting something used already loaded with an old OS. We want to be sure the FCP7 software isn't upgraded to newer version and/or doesn't import files to a version we won't be able to send back.

thanks in advance!