prior to 1979, cars didnt have emission controls. cars ran very well, and wasnt a pain in the a** to get to something and was easy to find the problem. when cars first came out than, they were clean just like a brand new car today. after years of many miles, parts do break done, wear out, etc. nothing lasts forever!! besides, why does an engine needs a crank sensor, cam sensor, starter sensor, etc, etc, etc. theres so many sensors on cars today thats pointless. if fine to have O2 sensors, and others for a car to run smoother, gets better gas milage, and all. (you have a '98 240sx that wont start. you dont want to spend mega bucks to find a poblem cause it wont start. you replace the battery, starter, and still scratching your head cause it wont start. after many money went by and time, you found out its a crank sensor.) i dont believe moveing the emission controls would make a car run rough, pollute, run rich, etc. engine may run a hair different, but not noticeable, besides, you'll have a cleaner engine bay
all a engine needs, is really the basics. if its EFI, have the basic needs.