Go get a vortec 350 from the salvage yard for $200. Put a quadrajet intake and long tube headers on it when you swap it into your truck. All accessories and water pump from your current set up will bolt right on. It will he 300-310 horsepower and 400 lbs ft at the flywheel. You'll have more compression, better head flow, and a roller cam. Plus stock driveability. This is cheap, dead reliable, relatively easy, and meets all your requirements.