I can't speak to 1975, Emily, but when I rode Space Mountain in early 1981 it was freakin' terrifying. Sudden turns, lights that were far — no, close! — and everything in near-complete darkness.
I rode it again about five years later and it was... very interesting. For some reason the total darkness was now just really, really dim light. That meant I could see the tracks and I knew when the turns and dips were coming. Lights that moved past us at impossible speeds turned out to be many lights that had the illusion of speed. Still fun, but the curtain had been pulled back and I could see how the magic worked.
Would you say the current ride was pitch black or just dim or something in between?