Assuming you are correct about "no sound at all" these are the possibilities:
Do you still have the clutch safety switch? That or it's associated wiring could be the problem.
The very FIRST thing I'd do, if you have it, is pull the wire from the firewall relay which goes to the clutch switch, and ground it. Just make up a short little jumper from the relay push-on term. to ground.
Bad firewall mounted starter relay
Corroded/ loose firewall harness connector
Connector on rear of ignition switch
Bad ignition switch
any or all "wire crimps" in between