Use a torque wrench to tighten them as you're measuring stretch. Sounds stupid, I know. But here's why I suggest that.
1. You can compare how much ultimate torque you have to apply to reach the recommended stretch amount, versus just tightening them to the recommended torque and calling it good.
2. You can catch a bad bolt by using the torque wrench. In other words, if you use a plain box wrench? You have no idea how much torque you had to apply to reach desired stretch amount. But if you're using a torque wrench and you find it only took 30 ft-lbs to reach the desired stretch, the bolt is faulty.
#2 sounds stupid/unlikely but i've seen a friend experience it with one bolt when building a 911 engine with ARP rod bolts. Better to be safe than sorry.
http://forums.pelicanparts.com/911-engine-rebuilding-forum/154552-arp-rod-bolt-wont-torque.html