340 Crankshaft bit the dust

OK here is the whole story. I bought the car in 2016 after a big flood here. The car had gone under completely. I drained the oil and water from the motor and flushed it with marvel mystery oil a couple of time. I then put fresh oil and pulled the distributor gear and turned the pump with a drill for a few minutes. I drained and did it a couple more times changing the filter also. I fired the motor and have been driving it sparingly for the last couple years with no issues. I want to drive it more often so I decided to pull the drivetrain and inspect it. That's when I found the crank problem.