Who ever said anything biased? I AM sporting a 347, but the 331 is still more reliable. My combo is pushing 516 at the wheels with a stock block, cast crank, 347 stroker, and main support. Any roller block can handle 600 horses with a main support. How long it can handle that is unknown, but part of DSS is about the build quality. We all know we could build a 347 but I'd tend to say that DSS's kit would last longer. They balance and blueprint everything, all the parts are designed to work with each other, every thing is triple checked, its done very cleanly, and the guys building the engines have done hundreds of them. You can get a lot of reliability by doing right. But I stand by my word that a 331 or 306 is more reliable than a 347. You really need to ask yourself how much horsepower you want to make. Then you can decide which block you need. The dart block will serve on the street but the motorsport block I hear has a tendency to overheat due to smaller cooling passages.