I don't think a montage is the way to end it on, but I do hear what you mean.
as is, it feels like it needs something more to connect it to alien; but all of the pieces that we really need are there: the derelict, and the transmission.
without its 4th act, it (this edit) ends right as it starts picking up. If I said 15 minutes were cut out, you'd all believe me.
I tried finding some use for shaws dream, that I cut out, somewhere before she died; but no sections worked out for me.