Correct harmonic balancer?

I guess my question would be, would the 72 318 balancer still be correct if I'm using a 69 340 forged crank? Even if I went back with a 72 328 crank I want to make sure the setup is correct. Thanks!!
Somehow I want to say I've heard something about different harmonic balancers for 340? We're going to need a guru to step in and answer that one...
I just know they can get rebuilt in people do re build them...