That's actually true. The 54 and up 331 and 354 heads are the best. They are actually more of a true Hemi design. The 392 heads are actually the worst besides the tiny round port 51-53 331 heads. Because of how the intake ports are curved more downward, because the 392 is a tall deck engine and rather than make the intakes different, they extended the intake ports which makes the intake ports on the 392 heads much less desirable. The hot ticket is putting the 392 size valves in the 331 or 354 heads.
