Harmonic balancer clarification

Okay, I know that the 340s had a mid year switch that went from forged to cast crank, and that each one had its own respective harmonic balancer, one of which was stamped on the back. Now, did the la360s all have the somewhat distinctive thick balancer with the sort of semi-circular groove machined into it?

Basically I'm going to look at a car and if it's like the last one I saw I won't be able to see the casting marks because of the headers, and won't be able to see the head stamping because of who knows how many coats of paint, grease, etc., and trying to find a definitive way to tell a 340 from a 360. The car is a '74 and was V8 swapped to a 340 in the last 20 years, but as they say - "Trust, but verify." :)

PS: I did search, but all I came up with were posts about buying or selling this/that, and nothing specifically like I meant... although my search terms or parameters might be lacking. :(