Leaky 340 Head Bolt?

I had an oil leak from the back of the engine.After seeing the rocker covers fouling on the inlet manifold. I fixed that but still had a leak at the back of the engine.I pulled the engine and found the oil pressure switch had been tightened too much and cracked the back of the block.
I veed out the crack aand filled it with JBweld. no more leaks.