I don't think anyone ever bashed the flat sixes. Not a lot of speed stuff (bore and mill) for flat sixes or ohv 223. I had a 53 with a first yr 215 ohv straight six. Bullet proof motor. Ya you weren't going to the drag strip, but you could drive to all of them.
https://cliffordperformance.net/
this guy ran inline dual ford 6 ohvs on a rail. did fine up on the hemi. I liked the sound of the 6. or the 6s
https://www.youtube.com/watch?v=sjZq5d_hTxA