I just pulled apart a 1954 235 with a by-pass filter that has run about 5,000 miles over the past 4 years and has had the filter element changed every two years (whether it was needed or not).
I also just pulled apart a 1960 261 engine with a full-flow spin-on filter (factory full-flow plumbing but after-market spin-on filter unit) that has run about 1,000 with the same spin-on filter).
Both engines look about the same under the valve covers.
I'd say the full-flow set-up is better but the by-pass set-up is quite adequate if you change your oil and filter regularly.
