SS trying to make me pay my deceased fathers overpayment

You should immediately contact a tax lawyer.

I am not sure it would be smart to hire a lawyer for such a small amount, we may end up paying him/her more than if we just paid the SSA bill. I just find it hard to believe they can actually do this.

You can pay for a one or two hour information session to find out if they can do that and what you can do about it. Seriously. It might be worth the money. It doesn't sound reasonable to me for a govt agency to wait 42 years to pounce on a family member who had nothing to do with this. They should have made arrangements for repayment with him, and I personally believe their mistake is their mistake and they should take no action. I have a hard time believing that, legally, the family is responsible. A quick one hour visit with a tax lawyer could answer that.

Failing that, you could call them, speak to someone else and ask about the situation. You might have been talking to someone who was recently hired and doesn't know the system. My sister worked in Tax Relief for the Canadian Tax Agency and she would get this type of situation all the time. There might be a similar department where you live.