WIth a roast, you generally want to cook to an internal temperature, not a time. But, when you lay it out butterflied, it’s thinner and more of the meat is exposed to heat, so if you were to cook it at 350 degrees at a 1/2 hour/lb. a 6 lb roast would end up ruinously overdone.lways position the pork roast in the pan so that fat side is on the top. Measure one tablespoon of olive oil in a small dish. Add 1 Tablespoon of dried spices to the oil. You can use rosemary, sage, thyme, or oregano; or a combination of these that equal 1 tablespoon.