Oil and oil filter technology have come a long way since the mid 60's. Have you seen some of the tiny oil filters that many manufacturers are now using on their new cars?I personally don't like the short oil filters, rather have a larger filter to do the job.
Regardless, the relatively crude engines in our cars don't need high oil filtration efficiency. In our cars the smaller filters will get the job done quite nicely and shouldn't present any issues given the limited number of miles and frequency of oil changes that most of our cars see. Using the small oil filters on my car for the last 18 years, the oil has been crystal clear at every oil change that I have ever done. IMO, based on personal experience, I can advise anyone that wants to go with the smaller filter that they need not be afraid of using it.