Marcus,

yes the Ronstan Orbits and the Karver blocks fit in the boom perfectly. I made up some custom cheek plates for the Harken sheaves and also a custom 2 sheave block to attach to the ratchet block.

ckuang.

down haul sucks into the front beam.
Rotation is under tramp.
Tack line runs down stbd hull (for access from trap)
Retrieval line / halyard are on tramp before exiting through tramp to the kite.

For equivalent purchase the internal mainsheet is cheaper, lighter and has less windage.