Good well proven engines. If it has the Sherwood raw water pump I would chunk that bugger overboard. Jabsco replacement is much better and way easier to work on. Check or change the exhaust elbow before it destroys the engine by rusting thru and leaking water into the cylinders. Quadrajets are good carbs (if thats what they have) until the secondaries open, primary venturi fuel control is excellent but the secondaries only have a rudimentary setup with jets and tapered rods controlled by a spring loaded flapper and a high speed pull over function. Read :very poor fuel control. If you have the Holley carbs,,, you have my sympathy. Some had Carter AFBs which are good, and very easy to work on. If you have points ignition changing out to the later HEI will help tremendously, especially on startup. These engines have a very good supply of parts available from the "hotrod" market place. If they are counter rotating one will have a gear driven camshaft, the other will have the standard chain drive. Distributers turn the same direction, crankshaft turns backwards on one engine. Fuel injection would be high on my list of wants. The 454 has been one of my favorite engines.