I did the Pertronix conversion a while ago on a '73 450SLC. It works fine but I cant say that I noticed a remarkable difference, as previously stated you have electronic ignition already and you also probably have the blue coil which works well so you wont see the same benefit as some older engines. I would recommend getting a flame thrower coil if you go with the pertronix setup and leave the ignition box and wiring in place should you ever reverse the change.
If you do a search theres some good information about the conversion on this forum.