"Home-Brewed" modified K Frame with B Body mounts

I remember back when I was in my early 20s, I put Big Blocks in 2 different small block cars without have to modify anything. 1 Dart & 1 Challenger. I don't remember what I actually did to make them fit but I didn't take moving and modify the k frame. Just wondering.
A big block swap into an E body with an original small block seems to be much easier.