The requirement for a OA visa criminal background check is about as vague as the check for elephantiasis. Go to your state LEO or county sheriff, not the FBI.
And yes, 40 year old criminal records can often be expunged. State laws are changing every year.
You need government approval to open a bank. Given that certain individuals, families and the government own the existing banks, how likely do you think it is they will approve your new bank?