I'm well down this rabbit hole.
Installation will be very easy compared to the crap I've gone through with my H16-44s and GP9s! Comparative loads of room in this unit.
For sound files, the only ESU sound file for FMs that currently exists is the 6 cyl mentioned earlier. They redid it last year with full throttle capabilities, so you'll want to download that one.
The H24-66 at Exporail is nowhere near running condition, and though I don't recall the specifics, is unlikely to ever run again. There were H16-44s running in Mexico relatively recently, but they may or may not still exist. The 4104 is now at Nelson BC. It was restored to very near running condition, but never quite got there and will probably be left to deteriorate now that it's been moved to a disconnected set of rails on the city side of the station. Having talked with Matt Herman, there's very little hope for another or improved FM sound file in the future. That pains me greatly.