Quick/dumb question- how to visually identify a 340 vs 360 vs 318 (with a 4bbl)?

Thank you guys for help.
I just looked at a "360" that I found on Craig's list but thanks to the help from this forum, I was quickly able to identify it as a 318 with a 4bbl. The motor looked good but he was asking a lot of cash and I have my heart set on something a bit more performance oriented so I walked.

I'd buy all of you guys a beer if I could! :D

So the junk yards around here aparently have no 5.9 Magnums...where the heck do you guys find your motors?