The photographs of the DC-8 70 series show the CFM-56-2 engines. These are single stage turbofans that produce 22,000--24,000lbs of thrust. The CFMs went into service in 1982 in a joint venture between GE and SNECMA. They are particularly useful for hot airfields and are also used to power the KC-135.
The older JT3Ds were first produced in the 1950s and stayed in production through 1985. The KLM Super 60 that you showed, has those engines and is one of about 8600 aircraft that did. When the DC-8 60 series shifted to the CFM, the series changed to 70
Now for your question. The super 70 series carried passengers (with United and Delta being the last scheduled users) in the USA until the early 1990s. This was a time when better performance and quieter standards of operation became the norm. Since the CFM offers about a 19% increase in power, some might argue that it is overpowered. But keep in mind that it makes a very reliable airframe quite attractive for serving a wide variety of airfields (economically) for cargo use. Airborne, Emery, BAX, and UPS utilize the CFM on their 8s. There are still a number of KC-135s in use with the Air Guard.
I would call it power improvement, not overpower