The USDA has published a roast beef temperature chart you can refer to while you're cooking. The chart also lists the approximate cooking times for various beef roasts. According to the USDA's chart, beef should not be cooked at a temperature below 325 degrees Fahrenheit. You can cook it at a higher temperature if you wish.
It’s important to use a meat thermometer for this roast, when the temperature is 60-62°C then the roast is done. I’d suggest using a digital ‘Instant Read’ thermometer, like this one, for the best results. The ultimate Sunday lunch or dinner, Slow Roasted Beef is perfectly cooked every time.
Generally, the final internal temperature, according to the U.S. Department of Agriculture, for a medium-rare pot roast should be around 145 degrees F after 15 to 20 minutes of standing time. The final internal temperature for a medium-done pot roast should be around 160 degrees after 15 to 20 minutes' standing time.
The perfect, slow roast beef. The long cooking time is ideal, as in the meantime you can get on with making your sides, setting the table and maybe even having a cheeky glass of wine while the oven does all the work.