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The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.
Harken "Big Bullet" block with swivel, model #146, will handle the job nicely, or any similar block from Ronstan or Shaeffer. I like Harken, though. The #146 will handle line up to 3/8". In Harken's Carbo block line, use a 40mm swivel block.
Iris' PO put stand-up springs on the blocks at the base of the mast, and I have removing them one by one. I think they aren't necessary, so I mention it in case a sales guy tries to upsell you. They really get in teh way if you need to swap positions of the blocks.
Notice: The advice given on this site is based upon individual or quoted experience, yours may differ. The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.