I have not used those heads , the EZ heads make a ton of power as well , the 440 Source Super Stealths are available as well & I have not used those either , either way buy good rockers , I have heard nothing good about 440 Source rockers .
Just so you know the 400 512 build is basically a race engine , the oil rings go over the wrist pin , the piston is extrememly short 400/470 or 440/512 seem to make a better street combo but I am not sure what the intended use of the engine is .