The 340 is the biggest POS V8 Chrysler ever made.
My own experience - I had a 67 Mustang GT fastback, 390 4 speed. Got it new in high school. My brother had a 69 340 Dart, automatic and 110,00 miles. I never could beat him in a street race. He sold it with 150,000 miles on it, the new owner took it to the strip and ran a 13.1. Impressive for the time.