In large saucepan, crumble and brown sausage; drain and set aside.
In the same large saucepan, Melt 6 TBSP butter. Add flour and whisk for 1 minute. Gradually whisk in 4 cups milk. Cook, stirring constantly for 1 minute. Add sausage, bacon pieces, mushrooms and pepper; set aside.
In a large bowl, whisk together eggs, evaporated milk, and salt. Melt remaining 2 TBSP butter in a large skillet over medium heat. Add egges, stirring until soft scrambled.
Pour 1/3 of sauce mixture into a lightly greased 13x9x2 baking dish; top with half of the eggs. Repeat layers. Top with remaining sauce. Place biscuits on top with points facing upwards. Bake uncovered, 20-25 minuted or until golden brown and heated thoroughly.