Oh, I sifted through the menus. I even grep -R'd the Quartus directory for different permutations of the part number....
Downloading 9.1 right now, thanks for the hint. I never realized they'd remove models like that - I figured maybe it was only in the paid version and they forgot to mention that or something...
...and naturally, it won't install.
Damn Linux, I love it when I don't require binary-level backwards compatibility.
Don't care to fart around with this, I think I'll let this junk bin part transfer to the rubbish bin, and grab a more modern one on the next Mouser order...