Well I don't have any good stories of speed in a stock bodied car. Maybe I'm not that brave.
But I do like to see what the flathead will do in my bellytank. Video was from the Ohio Mile last fall. They will breathe and rev ok naturally aspirated, just takes a lot of time, custom parts and $$$, to still not make a lot of horsepower. But it's loads of fun. Wish I had video from a few weeks earlier at Loring Maine when we were pushing just a little harder. Decided to back off a little when the tach peak memory was pushing 6800.
This engine has proven to like to pull to 5200 in high gear at Bonneville, Ohio, and Maine.
Andy
https://youtu.be/h5ta6dBwObA