Buns for Roast Beef Sandwiches

I have been asked to make a bun for a Roast Beef Sandwich. The Roast Beef will have a sauce/gravy over it. The sauce/gravy should be allowed to seep into the bread but be contained by the crust. Fingers should remain sauce-free when eating the bun. Does anyone know of a "Roast Beef Sandwich Bun" recipe? I think the last time I had a Roast Beef Sandwich was in Jack Dempsey's in New York around the early 1960's. I cannot remember much about it. Thanks Martin