I haven't thought that far ahead. I was trying to get everything mocked up and the chassis squared away before it went to body. But will probably go the cable route.
Yes, the kickdown , I was thinking the Lokar Cable kickdown may work? I know the original kickdown for the A500-518 is a cable.....need to investigate this. For my car I want a 518 behind a 440... so I would need the adaptor ring and crank spacer, I have a friend who put a 518 and 440 in a 56 Plymouth...but he isn't finished yet and the kickdown and shifter (Colum shift) is not completed. I am looking at floor shifted same as you.