In short, yes, it will work, multi mode has a bigger core then single mode, hence the wave forms of light "bounce" bigger waves then single mode and therefore go for shorter distance. Over 80 metres, as long as you're SFP are cheap and nasty, and it's a good fibre path, I think you would get away with it, but I would suggest for the long term to look at a more permanent and better solution, basically the correct media.
Ideally I would suggest you get a SM SFP, however I know they cost 4-8 times more then MM (Cisco anyway).
The other optional is a fibre conditioning cable, basically it goes in SM and out MM, again quite expensive for a cable but cheaper then a SFP.
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