I wouldn't worry about re-using them. Indeed, I re-used the torque-to-yield head bolts on my Chrysler 2.4L engine and no problem in 140K miles since, even though the FSM says to use new bolts. Figured I would just yield them a bit more and as long as no neck-down it "should work".

Along w/ grade, also consider corrosion resistance. The SAE Grade 8 bolts at Ace have a yellow coating (chromate?), but don't recall similar in their metric bolts.

Re torquing w/ lubrication in the post #12 link, oil on the threads does not change the torque to tension relation, according to a chart a former Rocketdyne engineer showed me (perhaps from NASA). A little oil on the threads gives more consistent torques. But, a high-pressure lubricant like molybdenum disulfide (even dry powder) can decrease the required torque by a factor of 2, and even more if under the bolt head. Of course, never fill the bolt hole w/ oil or you can get "hydraulic lock" and thus way under-torque it.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans