I'm not a doctor. I can't help but notice that when you mention the things your Father eats too much of, the problem may very well be the high refined carbohydrate content, not the saturated fat. It could very well be that the combined presence of both is more detrimental too.

In any case, it would be wise to actually measure arterial plaque over time, and other risk markers (Lp-a triglycerides, C-reactive protein, homocystein, etc.), especially if he's starting into a dietary change.

Track these variables over time, and this should provide a good assessment of whether you've put him on the right path, or not.