Sorry to continue the tangent,
I also recall a mod which used a spring to pull the mixture to "full rich" in the event of a mixture cable breaking. The design of the throttle body and also carbies on 0-470 would allow the mixture "arm" to gravity fall (aided by the normal vibration-Damn recips!) to "fuel cut-off".
Cheers,
I'm gone! (to check me mixture cable!
)