Gasoline smell in cabin
Another thing to check. As mentioned, Carter style carburetors cannot take the same pressure that a Holley can. In the picture below, the two red circles are where the float bowl vents are. After a WOT run, hop out and look to see if there is wet fuel around those openings. This would indicate the float bowl being overcome with fuel pressure and being pushed out of the vents. It would also explain why you're not seeing any leaks, because the excess fuel would be pulled right into the carburetor. You could possibly smell it, though.
Another thing to check. As mentioned, Carter style carburetors cannot take the same pressure that a Holley can. In the picture below, the two red circles are where the float bowl vents are. After a WOT run, hop out and look to see if there is wet fuel around those openings. This would indicate the float bowl being overcome with fuel pressure and being pushed out of the vents. It would also explain why you're not seeing any leaks, because the excess fuel would be pulled right into the carburetor. You could possibly smell it, though.