I have convictions going back to the 80's and 90's and I can't even get a visa to visit my children. I disclosed everything, I am now a paragon of virtue and they still said no. The thing is that US visa law is unique. They can turn you down just because they choose to, they are under no obligation to let you in and the rehabilitation of offenders act does not apply to VISA's to the US.
Sorry mate but I think you might be stuffed. I'm currently re-applying but I'm not holding my breath, although their staff are very pleasant and polite.