One more thing to add to what Ken said. Severe overtorquing could also be the reason for overstretching of the bolts. Remember that when you are torquing a bolt to specs, the design is to stretch the bolts slightly.

What are you using for lube on the bolts. Torque values are based on using engine oil. If using anti-seize or moly compound deduct 10% from your value. Do not try torquing a dry bolt. ARP has a good article on their website about the mechanics of torquing bolts, even shows how to measure your torque by measuring bolt stretch, which is far more accurate.

Thought about you Saturday, was at an antique tractor pull. Gonna get one of those ol johnny poppers going to do some pulling?

Fred
52 3600
69 C-10