Ian

Thanks for the reply. The holes are actually all identical, straight through smooth drilled holes, no threading or countersinks (the forward and aftermost holes had copious amounts of dirt around them when the picture was taken, making it appear to be counter sunk). The markings appearing to be counter sinks are actual the marks left behind from the forestay and backstay fork fittings on the original rig.

My intention is to use toggles on the stays and then attach a double toggle head block to each side (main halyard and topping lift aft and jib halyard and spinnaker halyard forward). I am leaning toward the toggle blocks so I have more weight bearing area as compared to using a U shaped shackle that would only bear on the edges of the holes.