The tension varies with the size of the standing rigging. The actual value isn't that important, what is more important is that they are all about the same. I would start with 15% of breaking strength for your uppers and about 12% for the lowers. Make sure the mast stays in column both port/starbord and fore/aft. Adjust the rear stay, if I remember correctly it is 600# on each leg of the split backstay. Check the mast rake. If too far aft, release some backstay tension, tighten the forestay half a turn, retension the backstay and check the rake again. When you have the fore/aft stays correct, double check that the mast is still in column. Go sail, if the leward shrouds show slack, tighten the shrouds half a turn each and check again. Back at the dock, double check the mast is still in column. Put your cotter pins in and have a beer.