Converting from positive ground to negative ground.
On the early cars 1965 and below the electrical system is positive ground. I picked up a 65 with a 1600 in it. The 1500 was replaced long ago. As a matter of fact there are a lot of non-stock things about this car. I probably rescued it from certain obscurity and I am not going to restore it to stock. She will get a stroked 1600 eventually. The first thing I wanted to do was convert it from a positive ground car to a more normal negative ground. This is not as big of a deal as you might think. About the only things that truly run on positive ground is the radio and possibly the fuel tank sender. That is if it is indeed the original radio. I replaced the gas tank with one out of a '66.
So the first thing to do after disconnecting the battery is to remove the radio or at least disconnect it. You might want to save it for the Smithsonian. Next you need to reverse the wires on the amp meter as the current flow will be the opposite of what it is now. Lastly reverse the wires on the coil. You want the positive terminal hooked to the hot wire coming from the ignition switch through the ballast resistor, and the negative terminal wire going to the distributor. Put the battery back in hooking up the positive side to the starter and the negative side to ground. And you are ready to fire her or him up. All of the other electrical devices should work just as they did or in my case do not. Pretty simple heh! I need to get everything electrical fixed-yet another thing to do.
I am going a step further and adding a single wire 60 Amp alternator from an '80's Chevy Camaro just like I did on the rest of my roadsters. I added a fusible link from the starter to the wiirng harness to protect the old wiring. Nothing like a little modern reliability in an older car. I also removed the amp meter and replaced it with a volt meter. Yep, she fired right off and charges just fine. She is pretty fugly right now but will some day will look better than new.