Stay with the 1.92 as this valve should be able to get you that amount of flow. A 408 engine really needs about 198 cc's of port runner and 315 cfm's or so, this head will never get this large without extensive rework.
Is this a general rule of thumb for a 408? Are you talking about an "all out 408" or a street/strip version? I am very interested in your thoughts re: this. I am coming up on now choosing the heads for my 408 and am still trying to figure out the best route to go for my application.
