I'm beginning to try to repair my R-3 SB Mopar. A few years ago it broke # 3 & 4 rods. They struck the block knocking 2 small holes, one in each side 1/8"-3/16" in diameter. It also put 2 hairline cracks through the 4 outer main bolt holes at position 2 & 3 main bulk head. The cracks didn't go into the water jacket area. I'm not a fan of cast iron welding. I've been able to use Belezone to do what I consider a good repair in the bulk head area. It would be extremely difficult to use a standard lock & stitch to repair the cracks due to their position. I'm planning on using the Lock & Stitch main & head thread repair insert kit. They seem confidant the process would work. Should I try to drill a small hole at the ends of the cracks ? I'll be using main studs. If everything works out the engine should make about 900-950 N/A.