torqueing mains and treads came out. now what?

I have several head bolt holes heli coiled, each time I tear it down it needs another, its a 1969 block and has been torn down numerous times, at least 20. You can only squeeze so much blood out of a turnip before its time for another. To heli coil a main bolt its gonna have to be drilled perfectly straight to avoid any side loading on the main cap and I would go ahead and line bore it after. The block is like the foundation on a house, if its not straight your gonna have a crooked house.