Unfortunately, cracks in that area of the 230/250 engine and coolant/oil cross contamination is a chronic problem. It's virtually impossible to repair. It's time to go looking for another engine, or at least a block.
Apparently, there's a hot spot that develops at the front of those blocks that promotes a lot of heat expansion and contraction which leads to cracking. The #1 cylinder is also prone to excessive taper wear. I've had to sleeve a few front cylinders to avoid having to bore all of the cylinders way oversize, or scrap an otherwise good block.
Jerry
