10 Rib Rack of Pork

Hello, I ordered a rack of pork for Christmas. It's about 7-8 lbs, 10 ribs. My butcher said to roast it for 10-15 min at 450, then turn the heat down to 350 and finish for 35-40 more minutes. But everything else I've read online says to go way longer than that, anywhere from 1 hour up to 2.5 hours. I'm going to use a meat thermometer so I'm not worried about getting it right, I'm worried about having all the other sides done at the same time. I don't want potatoes and veggies done when the pork has over an hour to go! Anyone have any tips?

I don't have the meat yet, so I'm not sure how fat/skinny/long it is. Would that have anything to do with it?

Thanks so much for any help!