Is there a general conversion for temp and time for a "traditional" recipe to a sous vide? Specifically I am planning on cooking a 4.5 lb Cross Rib Roast based on the Mojo Beef recipe from the "Pure Beef" cookbook by Lynne Curry. The recipe calls for roasting the roast at 250 degree for approx 3 hours until an internal temp of 180 is reached. I'm thinking of 24 hours at 165 based on recipes for other roasts. My rationale is that I don't need to hit 180 since I'm cooking the roast for so long and 24 hours to break down the connective tissues of the Cross Rob Roast. I'm also thinking of sealing the marinade ingredients (orange juice, lime juice, brown sugar, garlic, jalepenos &evoo) in the bag with the roast, letting it sit for 24 hours and then throwing it into the sous vide.