LS1INSIDE

so i'm rebuilding small lsx motor, off a 2002 ls1 block, but i ran into a snag when i was bolting up the heads, i took every precaution, when cleaning deck surface and drying and cleaning head bolt passages, but upon reaching the second torque sequence the long middle head bolt stripped the threads off the block, anyone ever run into this or know where i can find a helicoil kit, i've read of the timeinserts but seem a bit expensive for just one head bolt, and i've also heard of using a 7/16's stud, what's my cheapest safest alternative...