I bought the Imperial Services cable when I went to a newer 727 (sb) in my '65 Belvedere. After a minimal amount of adjustment, I'm very happy with it. One thing I did counter to their instructions was use the later detent ball spring. It's stiffer, making the shifting at the lever feel a little more positive. The only downside was that it took about 6 months for them to ship me the cable kit. Charged my card the day I ordered it, of course.

In order to know what you want, you'll probably have to find out what you don't want.