Round, by its nature, is a chewy, well flavored beef cut. It is a well exercised muscle. To salvage what you have, and make it edible, there are a few things you cando. Find the grain of your left-over chunk of meat, and slice,it as thin as you can against the grain. You can then use the slices to make sandwiches, dipped in au jus, or use in a pho type of soup, or make into a Philly Cheese sandwich. You can also make hot, open faced sandwiches with gravy, or for enchiladas, burritos, tacos, etc. ch9op and add to beef pot pies, or mix into beef-pepper dishes (pepper beef). They would also be good in manty Asian dishes, or shredded and mixed with you favorite Mexican sauce. The thin beef slices would be good in a slow-cooked pasta sauce, or ina stoganoff. Stir fry it with mushrooms, and a Bechemel sauce.The idea is to not cook the meat, simply heat it so that its robust flavor compliments other items. I;m still thinking some kind of sandwich, maybe with peppers, onions, ansa little horseradish might serve you well.
Good luck. S far as what you were trying to get, some good cts include skirt steak, hangar steak, rib roast, Inside round, flank steak, brisket, tenderloin, sirloin roast (end closest to the rib).
Roasts to top round, bottom round, rump roast, tri tip,anything from the legs avoid for medium rare are chuck, neck roasts.
hope this helps.
ZSeeeeya; Chief Longwind of the North