Ok, I haven’t seen to in years and years, but I was just discussing scary movies with my dd last week, and I mentioned When a Stranger Calls. The one from 1978-79, or thereabouts, not the remake. It has more tension than gore from what I remember, but maybe I’m wrong. It is free on Netflix so I started watching it and yes plenty of tension. But I only watched the first half hour. You might want to zip thru and see if there’s gore.
Edit: oh you said not before 80’s. So close.
Another edit: it’s on Amazon, not Netflix