This saying is attributed to Metrodorus.
Here is the manuscript of VS47
(Source: Vat.gr.1950, part 2, 403verso)
And here is the text in Metrodori Epicurei Fragmenta collegit scriptoris incerti Epicurei Commentarium moralem, subiecit Alfredus Koerte (p.561)
That famous word "triumph-song" does not appear in the manuscript! It is a "correction" by Usener, clearly shown in the manuscript itself and in Note (5) in Metrodori...: 5) πλειονος V[atican]., corr[ected by] Us[ener]. Usener corrected the manuscript's πλειονος (more, comparative degree of πολύς (polys)) to the more dramatic παιωνος (a song of triumph after victory; a choral song addressed to Apollo or Artemis)
Epicurus Wiki has a nice breakdown of the saying (including Usener's "correction") that is helpful in providing context and appreciation of Metrodorus's contribution to our surviving texts.
I'd be curious what Bryan or @Twentier or others make of the manuscript's πλειονος versus Usener's "correction." If we take the manuscript at its word, something like: we shall depart from life with/in the midst of/along with more beauty/nobility (μετα καλου πλειονος), exclaiming/proclaiming that we have lived well.
Or something like: We shall depart from life proclaiming that we have lived with more nobility (than others who didn't pursue pleasure?). ? Thoughts welcomed!