K-frame question

I didn't know whether to put this thread in the /6, or small block forum. My car was originally a /6 car. The previous owner replaced the /6 with a 318. I was wondering what the differences are, if any, between a /6 and small block K-frame. How could I tell whether or not the K-frame was replaced when the /6 was replaced? I'm planning an engine build this upcoming winter, and when I pull the 318, I would like to put a 360 in it. From what I understand (Ex-GM guy here) going from a 318 to a 360 is like going from a 305 to a 350. They have the same bolt patterns, so I shouldn't run into too many issues.