[truckster]

I recently was facing a similar question. After much research, I decided on a Vortec block and heads. The Vortec blocks have several advantages that are going to contribute to your goal of HP and torque and longer life. The one-piece rear seal rarely leaks; you get a true roller cam (no chance of a wiped cam and better torque); and if you go with the Vortec heads you get the best-flowing SBC heads ever made by GM. The one I've built is mostly stock with an upgraded cam (HT 383 cam) and HEI and remanufactured Quadrajet. It's good for around 330 HP and close to 400 ft-lbs of torque.