Cost of engine replacement or rebuild

I have a 125,000 miles on mine now with just spark plug, wires, distributer cap and rotors changes. As Bud said I worry more about the transmission, so I change the filter and fluid every 30,000 miles or so along with the rear end fluid. I think Headers, FF muffler sans cat, and a CAI will help it run cooler, add about 80 HP, and give it a longer life. 454's run hot so these mods will help it run cooler which will add to the engine and transmission life. My engine uses about 1/2 qt of oil between oil changes every 7000 miles or so. Every 3 years or so I run Seafoam or Berriman's B-12 through the TBI just to keep the top end clean and every 5 years through the crankcase. Syn oil will also keep the crank case clean. A friend had a crate engine install for about $9000, watch the heat and maintain it and you will see 250,000 miles if not save $10,000 for an engine replacement.