Hey does anyone know of a good reference document for what was original to various S30 Models - first series - wheels, carbs etc.

I believe you are referring to what is commonly called "Series-1" cars.  The thread below is a good place to start but there is information scattered all over this site and other Z websites.  Try Google'ing 240z Series-1.

http://www.classiczcars.com/topic/6982-240z-differences-1970-1973/