I remember when Chrysler sold their inventory of "452" heads for $30 and later $15 apiece and all the people with those NOS heads said "906" and "346" heads were absolute junk and you had to have (their?) "452" heads to make any power, at a premium price. They even promoted "hardened seats" (induction hardened castings at the factory, NOT pressed in inserts) and installing oversized 1.81" valves in the same breath. Many salesmen out there!
Chrysler/MoPar Perf/Direct Connection really missed the boat by insisting on using stock length valves in their aftermarket heads, iron and the aluminum Stage VI. Also they cast them with huge/restrictive guide bosses (Stage VI and iron R/T Magnum heads, in particular) and weird ports (aluminum Magnum/Commando intake and exhaust), but when ported/cleaned-up, the other superior features gave them an advantage.