There are a couple serious flat head guys up in my neck of the woods and I was gabbing with one just a couple weeks ago.
One of them has a front motor dragster that runs stock blocks and has allegedly run in the 7's.
They use a girdle on the bottom end that essentially is a bottom end in a box........includes the caps and ties into the oil pan rails as well.
I got to work on a couple of them in high school auto shop and the rods were what scared me.
But there is still fairly significant aftermarket support for them , and some die hard fanatics who run them.