I just did a 2 to 4 bbl conversion on my 1966 383 and all went fine. But ofcourse the linkage was just not right. So I got a throddle cable bracket from a 70 Cuda 4 bbl and that fixes the throddle problem. And I think the kickdown is also ok, should it not be just about touching the stud when the throddle is resting? Had to bend the rod and adjust it out. The travel seems to be about the same, and it seems to shift fine. Just nervous about the transmission.
Joe

 

Is this at the carb that you are talking about (It's been a long day and I'ving issues thinking right now)?

If so, maybe these pics will help you out.









This is setup on a SB with a 600 CFM carb, but they should be set up the same.

 

First is a pic with the old linkage and 2bbl, then are the pics with the 4bbl and new throddle bracket.