You will definately want to make sure the piston choice is right. You can use flat tops, but my first choice would be KB362s for cost, reliability, and ability to build in tight quench for the Magnum heads. Have the block blueprinted and set the static compression around 9.4:1. Then put a decent cam (something like the HR268HR-10 Comp) in it. With an Air Gap and 750cfm carb you'll be making some decent reliable power.