Hi Peter,
We have blocks and swivel jammers and have been happy with the result. Although we used ratchet turning blocks on Cockle we always seemed to leave the ratchets disengaged, so I didn’t bother with them when re-fitting Shearwater last year.
Not using the rear benches provided a space on the thwart and some spare material to make a transverse wooden mounting block/pad for the turning cheek blocks, one either side of the boat. They’re immediately aft of the front bench ends.
I haven’t seen sheets cleated right across the boat, but it might be helpful when singlehanded either to tie the ends of the sheets together or rig the genoa sheets continuously, with the ends tied to the genoa clew. Either way guarantees that you can reach the sheet without leaving your windward perch.