That will roast ok but not great, and it definitely won't low n slow, no fat no collagen, except the little strip in the middle.
Marinate the heck out of it, run it at a regular 350 or so to a med rare mid 130s, rest it or even chill it and slice wicked thin across the grain for some good sandwiches. Thats a plan.
A sirloin beef tip, bound with cord. For best results a sirloin tip either a minimum weight of 5 pounds should be procured. Results are better with larger tips up to 10 pounds. Black pepper Crushed garlic corns Worcestershire sauce.
1. Completely thaw the sirloin tip.
2. Crush several garlic corns thoroughly. Add equal parts of salt and black pepper. Make a "slurry" adding Worcestershire sauce. Make 5-6 tablespoons of the slurry for a 5 pound tip. Increase as required for a larger tip.
With a sharp knife make several deep vertical incisions in the tip, just large enough to be opened up with a finger. With a small teaspoon place some slurry in the incisions and work down into the meat with a finger. Rub any remaining slurry over the outside of the sirloin tip. Place a meat thermometer in the center of the meat. Place in oven and roast at a temperature of 325 degrees until the thermometer reads "rare", "medium" or "well done" as desired.