FYI the Extreme Package from K&N comes in 3 base styles. One is flat, one is a mild drop base, and the other is a deeper drop base. You could have used any under the hood of the Backdraft depending on what you needed.
You may also have been able to add a spacer under the carb, which is always a benefit as well.
Dropping down from a 14" to an 11" is going to negate any possible benefit of going to the filter top
due to the decrease in diameter or really the circumference.