You'd be looking for SARAH. The link is to the Digital Tradition file here; the line is usually "won't you come out tonight", which is probably why you weren't able to find it.

See also these earlier discussions:

im looking for chords to 'Sarah'  (the link is to the only post that contains substantive information).

Sarah: Traditional Newfoundland Folk song

No information there (or elsewhere on the web, so far as I can see) taking it back much beyond the 1950s. On the face of it, it looks like a popular-style song of the late 19th or early 20th century, but that's guesswork based on the writing style, and I haven't heard the tune. At any rate, it's very unlikely to be anywhere near old enough for your purposes, and it doesn't look Irish, either.