In this case I agree with @Bewy . This is a good example of a mismatched combination. Compare the power curves with the 408 I tested last week. This only peaked 500 rpm higher with 43 cubes less and pretty much the same heads with a cam with 2 deg more LSA and 17 deg more @ .050" and a decent single plane intake. Conventional wisdom would have us believe this engine should have peaked much much higher than the 408 did.