Will this comp cams kit require machine work?

He never mentioned he had magnum heads. That kit will work with your engine and doesn't need machine work to the heads. Install the springs with the retainers and locks, then stab in the cam and lifters. Don't forget to buy intake gaskets and timing cover/water pump gaskets. You'll also need break in grease and break in oil to go with that cam. Make sure you have everything correct as far as ignition/valve timing before you crank it up. As soon as it starts, hold engine at 2000 rpm for at least 20 min.