On the transmission inte only real modifications you need to do is to trim the Omni's transmission mount to fit the 568. Easy to do, try to put it on and you'll see where you need to trim. The other is to make a spacer with a long bolt for the bobble strut mount on the k-frame.
I don't know about the cables. I kept the rod shifter when I installed the 555 in my GLHS. If interested I can give you the address of someone who can make the needed brackets to keep the rod shifter with a 555 or a 568 trans. PM me if you're interested in that.
A forum community dedicated to Turbo Dodge owners and enthusiasts. Come join the discussion about Shelbys, Daytonas, Chargers, Omnis, SRT-4, performance, modifications, troubleshooting, maintenance, and info about all Mopars!