Well I just downloaded the Falcon 4.0 from GOG, it is a much older looking thing than what I played a few years ago. What I played is probably the version in my link to the Amazon site in my OP.
Anyhow I cannot get the BMS installer to see my GOG version of Falcon 4.0 when it asks for the folder. The installer’s “next” button wont highlight no matter what folder I click. The Falcon 4.0 is in c:\GOG Games\Falcon. The installer opens it one step more to \Documentation and \Video Codec but no more. And whatever i try to point it to the Next does not light up. I have two other versions I haven’t downloaded yet from GOG that came in the package I will try those, but I thought I downloaded the original one.
Also apologies about my saying “endorsed”. What I meant was that it is the one referred to in the FAQ as one of the ways to get the original 4.0 (not bugged, and it works etc), not that BMS somehow officially endorses GOG.