Joe,
Two boxes (20 spokes per box) of DT spokes will cost less than $20 (Nashbar). Why go to the trouble to build a wheel on a new rim with used spokes. They are probably fatigued and who knows what the crash might have done to them metallurgically? I think most people would tell you use new spokes. I don't think I would even use the old ones for spares. Spokes are just too cheap to take chances with. I have saved some broken ones. They look like they might make great shish kabob skewers. Grilled shrimp a la velo, anyone?
Regards,
Raymond