Yeah you want to cut the fat off if there is alot, just use how much fat is on a whole chicken as a guide, I personally wouldn't give any more fat than what would be on a chicken, especially for a newly raw fed dog or one that seems to have a sensitive stomach.
Here is a link to a site I refer to, if you go down to the bottom of the page you will see photos of a Dobe called Bowie eating beef ribs, I just wanted to point out that they are very good to give but they may not be able to eat all of the bone - in which case you give them their ribs and when they are finished take away the parts of the bone they can't eat

. I haven't tried pork ribs yet (they have been quite pricey) but as whitedaisy mentioned they are smaller, and when I look at the other bones Ruby can get through I don't feel she will have a problem eating all of it.