MastHead Shivs for a Cal 2-30

[Scot Henry]

Would anyone know of the size limitation for a 1968 Cal 2-30 masthead shiv?

The boat currently has very worn wire-rope halyard and I would like to replace it with rope alone. Any ideas? I've been to the top, but because of the fractional rig was unable to get a really close look and measurement. Hopefully next time I go up I will be more preppared.

 

Thanks

Scot