Take a look at the O'day Daysailers forum here:
http://forums.sailboatowners.com/index.php?forums/day-sailers.66/ It's for boats like ours, the smaller O'days.
We have discussed this some over on that forum. O'day's rigging directions say to only rig things hand tight. Since this boat (and my 192) are not part of a racing class, there aren't any other rigging guides out there. (Most one design racing classes tend to have some rigging instructions with rig tension numbers prepared by some notable winning racer or another up on a class website...) Further to this, it's a cruising daysailer/overnighter boat, so it isn't really designed to carry large rig loads.
Seldén Mast makes a general rigging guide for a variety of rigs. They often recommend a starting point of a rig tension of 10% of breaking strength of the stay wire. With 1/8" wire and a breaking strength of @ 2,100 pounds, maybe a forestay tension of 320 lbs, uppers 240 lbs. On this boat, I think that can be a bit high. I think the rig should be tuned to keep the uppers tight, and the lowers looser than that, but such that close hauled in 10-12 knots, the leeward shrouds loosen but not visibly so. If your lowers are too tight, you may be pulling out the pre-bend of the mast (mine were.) The mast needs about .75" of pre-bend, and backstay tension will make the tip of the mast above the hounds look slightly kinked aftwards.
Here is the link to the Seldén Mast tuning guide:
http://www.seldenmast.com/files/1456145028/595-540-E.pdf