would have had to

Which is correct:

[color=red]1-If I had been there, I would have had to help him. I don’t know if I would have or not. but I would have had to.

[color=indigo]2-If I had been there, I should have helped him. I don’t know if I would have or not. but I should have.

Gratefully,
Navi.

I wouldn’t use ‘should’ with that ‘if I had been’ structure.

I would use
I would have had to help him
or I would have helped him.