I think a 383 build would be better for the Blower set up . The 400 SBs are great . But with the steam hole set up in block and heads . They do run hotter then the 350/383 engines . And with that 6-71 blower that engine will really heat up . With a well built 383 and that 6-71 blower ? You should be just over 600 HP with 10lbs.of Boost