I believe you're thinking of the SBC-type distributor where the points were adjusted with an Allen wrench through a window with the engine running. With the distributor at the back of the engine, that was about the only practical way you could do it. You hooked up a dwell meter, stuck the Allen wrench in through the window and turned it until you got the right dwell setting, and bingo, your points were adjusted. On the sixes, it didn't work that way. You had to pull the distributor cap off and set the points with a feeler gauge like on most other engines. None of the inline sixes ever had a window-type distributor cap.
My recommendation would be to ditch the points and install a Pertronix conversion, which is really easy and gives you a permanent dwell setting and is more accurate than points ignition, plus it retains the stock appearance of the distributor. Also, if you ever want to go back to using the points, it takes about 10 minutes to change it back.
