Help identify the opponent

The folk at Heidelberg have unearthed some old footage of South Melbourne at Middle Park from the mid-1970s. They've posted a snippet online, but the identity of the opponent (in the blue shirts - South is in the white) is unknown.

Can you help identify them? The only clue as to the date is that the game was played in either 1972 or later, because Winfield cigarettes - whose sponsorship is viisblenin the background - were launched in 1972. It is possible that the game was a pre-season or other sort of friendly, or a some sort of minor cup,

@smfc we have come across some old footage of Sth mid 70’s. We are not sure who the team in blue strip is but white is Hellas. Amazing whats still out there. We stumbled upon it as part of our club anniversary research. Contact us for a copy @smfc pic.twitter.com/lZzZY1cPYx

— Heidelberg United FC (@HUFCWARRIOR) December 19, 2019

My guess, based on the limited research one can do on these things, is that the opponent was Box Hill, who had jerseys like the mystery opponents in this clip in 1970; and it is possible that they used them again later on as an alternate or spare strip. But that's just a hunch.