1Heat oven to 375°F. Separate dough into 8 biscuits. Brush top and sides of each biscuit with margarine; coat with bread crumbs. Place 2 inches apart, crumb side up, on ungreased cookie sheet. Sprinkle any remaining bread crumbs over biscuits.
2Bake at 375°F. for 14 to 16 minutes or until golden brown. Remove from oven; cool 5 minutes. Set oven to broil.
3Meanwhile, in small bowl, combine 1/3 cup mayonnaise and green chiles; mix well. Split biscuits; place tops and bottoms, cut side up, on same cookie sheet. Spread mayonnaise mixture evenly on top halves of biscuits. Arrange roast beef slices on bottom halves, folding to fit. Top with cheese.
4Broil 4 to 6 inches from heat for 2 to 3 minutes or until cheese is melted and mayonnaise mixture is bubbly. Place top halves of biscuits over bottom halves. In small bowl, combine 1/2 cup mayonnaise and mustard; blend well. Serve with sandwiches.