383 build strip out head bolt holes

When I was installing the heads I torque them at 20 lbs. then to 45 lbs. and pull the threads out of the center head bolt hole, its a 1975 350 (010) block it had a lot rust in the rear of the block when I remove the freeze plugs I guest the water does not flow in the rear that much so I went with a intake that has the water passages in the rear to circulate the water throught the rear of the block to the front at the thermotstat housing. Here are some pictures of how I repaired the head bolt holes. I started with taping off the block, checking the threads in the other holes and numbering the threads in each hole and replace the bad ones , Its going to have a lot of compression so I wanted it to seal good, I replace 4 bolt hole threads with Heli-coils, drill them out and tap the hole and install Heli-coils in the holes used red lock tight on the Heli-coils.When I drill them out I used grease on a magnetic to get the shavings out, then clean the magnetic and just put it in the water passage to get the rest of the shavings out it work out very good. Just have another person to look to see that the drill and tap are straight when doing this, I did'nt have a guide that would have work better but you have to do what you have to with what you have. LOL