Hello Dean, I did the same to my base, then we straped the car on the chassis dyno and the results were very poor, when it came to the cfm flow and the motor was also,.... lean. So, I had the intake carb flange planed off apx. 1/4" and I now have good hood clearance with no effect on the cfm.
With a 14" round (or so) air cleaner with a drop base, I doubt it would hamper cfm at all because 3/4" of the filter is above the carb. With our short height 1-3/4" oval air cleaner, you really reduce the air intake to the carb.
Be careful.
