How much does a hood scoop actually help?

I didn't bother with a scoop for my streeter, which seldom sees over 65mph. But I bought a nice oval aluminum air cleaner housing and mounted it on top of the hood, between the inserts.

I had to run a scoop because the throttle body wouldn`t clear, even w/ a drop base air cleaner.
I didn`t really want to, much like the roll cage, but needed the scoop, and the cage to stop the body from twisting . We twisted a 67 hemi belvedere body back in the day.