Your best bet would to attend the Amherst Rail show held at the Big E in West Springfield which unfortunately has already occurred back in February. You will find whatever info there is about these areas. If you don't want to wait, you cold join the Amherst Railway Society who sponsors these shows. They meet once a month. You may find what you want at a meeting,or, at least a good lead. The Easthampton yard was adjacent to the apartment my parents had when I was a child. I spent many days riding around the yard in the New Haven switchers with the crew. I wonder how many people know that New Haven actually interchanged with B&M here also! A number of times I got to see 2 different railroads drilling in this same small yard. One time a new Haven Passenger train came through! I remember seeing the people looking out of the streamlined cars and waving to the little kid looking up at them. Somehwere I do have a sketch of the Easthampton yard that I drew up before the tracks where removed. At the very least I can tell you where to see one of the engines that plied these tracks is, although only to Easthampton. That would be the Danbury Rail Museum in Ct. They have a New Haven Alco RS11 #402 which became Penn Central #7662. I would see this engine rumbling into town with as much as 12 to 15 cars in the 70's.
RAILROADS: AMERICA'S MOST IMPORTANT TOOL FOR ENERGY CONSERVATION. REMIND YOUR POLITICIANS HOW YOU WANT YOUR TAX DOLLARS SPENT.