Crankshaft, rods with 3/8" bolts, camshaft, lifters, block with date code, heads with date code, intake with date code, heads with spring pockets, intake manifold, exhaust manifolds, damper, timing cover housing, valve covers, carb, distributor, coil bracket, accessories brackets all are important. Pistons, valve size, camshaft, can be changed for a rebuild and still be considered 289 HP. I agree with previous post that you should build another 289 and keep the original HP together. The 289 4V is not considered a HP, but the 289/271 horsepower is the real HP. It will be worth more that way. Joe-JDC