No, the early iron block 450 is the most reliable engine. The earliest (72-75) had the D Jet fuel injection system, though, and it was problematic. The 76-80 models had the K Jet, all mechanical fuel injection and much more reliable. Also the least expensive of all the fuel management systems to work on of all 107 model years. The 560 is a nice engine, but it wasn't as solid as the 450.