I made some simplifications/assumptions, but this is my approximation of the Predator intake opening cross-section.
I could be wrong.... But if somebody else calculates something close, I will go with it.

For comparison, my B1 original heads were ported by somebody to 2.74 x 1.755 with maybe 0.50 radius corners.
And I came up with 4.59 sqin. A standard Koffel's gasket is 2.66 x 1.60 or about 4.04 sqin accounting for corners.