Re Wiring the Dart Question

I am thinking of doing all the wiring myself and was wondering what wire and where to purchase should I use...I was also thinking of maybe stepping up a gauge or two in sizes especially on the ignition side of it...is this cheaper or would I be better just buying and aftermarket harness? I have heard some of these aftermarket harness's arent that easy to do so I thought I'd do it myself...I have taken over a hundred pics of all connections etc.