Another blast from the past inspired by the Supplimental Freeway System found by Revive 755.
I was doing a Google search on FAP 431 (what became I-355) when I stumbled across the Year 2000 Plan made back in 1980.
http://www.cmap.illinois.gov/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=6666
Technically that system was found by someone else on MTR a few years back.
From Page 21 (or 35/96) it seems the South Loop Distributor had been downgraded from a freeway grade facility by the time of this plan. One of the plans from around the time the Crosstown I-494 route was canceled had it planned as a freeway from the Cermak Road spur off I-90/94 to Congress Parkway.