351W is better built with larger main and rod bearings. It also has a taller deck hieght which will help it live longer. Also if you ever notice the chevy heads have two exhaust valves right next to each other in the center of the head E-I-I-E-E-I-I-E, where as the all fords go I-E-I-E-I-E-I-E. The heat is better distributed thru the Ford Heads than Chevy Heads.