500 Hp Slant 6
A turbo seems the way to go. It's going to have to be a stout motor NA to make that kind of HP with so few cubes even with forced induction. Be sure to upgrade the brakes and if you take it to the track don't be surprised if they ask you not to come back with out a bar or cage. My calculator shows 10's with 500 HP and 2800 race weight if you can hook it up.