NACRA 500 Jib Furler Rig Halyard Length

Anyone out there have a recommendation for the length, diameter, and type of line for NACRA 500 jib furler rig halyard? I will use a loop with the wire halyard inside the zippered luff. I most interested in the length but other parameters welcome. Thanks.

I was going to just buy something the length of the mast but that seemed to be wasteful and imprecise...