I went out to a junkyard today that I thought might have one, but they said they didn't, one of the old guys spent a half hour out in the yard looking but I wasn't allowed to go in "for insurance reasons". Yeah whatever lemme go look for myself, I know better!
Still in the market for one.
If the longer / shorter kickdown lever is an issue, maybe one reason that I never had a 904 problem (except for the time I stripped the splines out of the torque converter on a high rpm 1-2 upshift) is that I always modified my valve body accordsing to Mopar magazines of the time, drilling a few holes a little bigger in the separator plate, and I always cranked up the line pressure adjuster screw as well.
I know of 2 other junkyards that might have a Super Six setup, but it is a slim chance at either one.