318 tear down... it’s about time.

Iv seen that 400hp build several times pop up on my search engine while searching for 318 building tips. I remember reading one years and years ago in a mopar muscle mag using a stock bottom end I dont recall the hp. I'm curious why a 273 crank it's the stroke as a 318?

My guess on the 273 crank, is to get a forged crank. Still the same stroke though.