I'm not as hardcore as some in this particular forum but I know that Car Craft did an article on various sizes and the losses of air filters on a pretty robust engine- it was on a dyno though. Carb inlet size is only so big- it is more about smoothing and directing airflow than filter size- carbs need a flat flange surface leading into the carb itself . For a snorkle style scoop, you may be able to get some additional filter area by going with an oval air cleaner.

I did a quick search and found these two references. May not have been the same article I was thinking of but it is a start. I thought this was interesing:

Car Craft April 2002, Filter Test....Page 72 & 73
1. K&N #E-3403, 7"X3"....49.5 SQ.IN..........520 Horsepower..........0.8Hg vac
2. K&N #E-3770, 14"X6"...230.9 SQ.IN........520 Horsepower..........0.6Hg vac

HOT ROD - JUNE 2002 - "AIR FILTERS SHOOTOUT"

Using 14"x3" filters, each half covered with duct tape before the test began, using only 1/2 the filter area.

1. Advanced Flow Eng. (AFE):.... PN 10-10009..$59.56......... 365.9 HP
2. Holley :............................... PN 220-5.......$39.99.........367.2 HP
3. K&N Engeneering:.................. PN3737.........$69.93.........368.7 HP
4. Purolator;............................ PN A60074.....$5.99...........368.7 HP
5. Rush Performance;................. PN 710048.....$44.30.........368.5 HP

I hope this hels.