Going to do my first large beef roast. I did a 5 lb prime rib a couple weeks ago for the first time and it was excellent for sure. This one is a little bigger and it is a top sirloin. I stopped at the butcher today and he fixed me up with a great looking piece of beef. This bad boys is 10lbs even. What I would like to know is @ ~230 F how long should this take. I would like to have it done to medium in the end. I am going to leave a nice buffer for time as well because I plan on wrapping it and setting it in the cooler for at least a hour while I work on other dinner items. Any help, advise or words of wisdom are greatly appreciated from this experienced bunch!