Strange, I'd never noticed it with my Volna 80 (or my Vega 90). I've got a roll of Delta3200 I shot yesterday with it, I'll see if there's anything swirly there.
But more than likely I just haven't shot the right scene to show it off.
The best lens that I've got for that effect is the Cyclop (or Helios) 85/1.5 for 35mm. That's equivalent of a 135/2.4 on a 6x6. I still get some swirlies with that lens on my d***l, that's like putting a 215/3.8 lens on a 6x6.
But there's no equivalent to the cyclop in 6x6 unfortunately, without going to a real brass petzval...