EGR or not

Help! My son recently bought a 1974 Duster with a 318 and three speed. He decided to replace the two barrel with and Edelbrock Performer and small four barrel. When he went to order the manifold he asked me if he needed an EGR or Non-EGR part. I assumed that the car was non-egr as there is no air pump. Upon closer inspection I noticed that there are vacuum lines that run from a fitting on the radiator to a valve of some sort on the stock manifold. Does anyone know how all this works and can I eliminate it. Also what is the difference between an Edelbrock EGR vs non EGR manifold. Any of you California guys out there who have run across this and can help me out. (Or anybody else). Thanks a bunch.