The 5.7 liter chevy small block (LT-1, the only 350 available was in the Z28) puts out 360bhp factory fresh. You can get it near 400 bhp with minimal improvements. My Dad's 1976 Monte Carlo had an LT-1 and it was putting near 380bhp at the wheel with aftermarket headers, holly carb, mini-fireball heads, and a hand made forced air induction system. That thing was a beast.
God I loved that car.
Incedentally, the Monte made about between 8 and 5 mpg highway.