Slant 6 904 TorqueFlight question

As mentioned, the push-button shift/park cables go direct to the tranny, so that shouldn't change from anything you do to the engine & intake.

I think the problem is that there never was a factory 4 bbl carburetor on a slant, assuming that is what you have now. Thus, you need a custom cable kick-down. Push back on whoever is telling you half-truths.