All you have to do for the kickdown linkage that attaches to the carb is lengthen it about 1"-2" and it will work with the 4 bbl throttle bracket.
I would just buy some threaded rod the same thread as on the linkage rod. Then get some hex stock larger diameter than that and drill and tap a hole for the thread for the linkage rod. Then Thread part of it on the old kickdown rod, and then put some of the threaded rod in the other end and then you will be able to adjust it properly.
Sorry for the late reply, I tried to reply yesterday, but I'm having modem problems and not staying connected or able to post...