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Excellent advice, Cary.
I have another suggestion. Ask all your relatives - at least the ones who are not estranged - to come up with just one positive thing about your dad. String these together, and add the autobiographical stuff like education, job, etc. and you'll have enough. A eulogy doesn't need to be long, just semi-sincere sounding. (I read an article shortly after Saddam's death in which someone managed to come up with a few positive attributes for the man.)
My granny's children did this at her funeral. But then she was a pillar of the church, a fabulous mom, etc. Still, no one is all bad. We all have demons we struggle with. And death tends to sanitize the past remarkably.