Does (1963) 225 engine have crank shaft pulley/Harmonic Balancer Bolt?

I am rebuilding my engine and my mechanic says the Bolt for the harmonic balancer/Crankshaft pulley is missing. I did a google search and another forum is saying there is no such bolt. I am not a very technical person. Can someone please explain which is correct and if yes where can I buy one for him? or the specs of the bolt Thanks.

1963 Valiant signet 200 225 slant six stock engine.