Alternator

So I am setting up a Dart for track only and I need some help on the correct alternator. I am being told that I should get a 1 wire alternator. I know nothing about this. What year were they used so that I can get one that will work with my set up? how big 200 AMP ? Too big? I am going to be running a 318 for now and will be upgrading to a 440 in the Future. If I could get one now that would work for both applications that would be great. Any ideas ?