260 or 289

I have recently purchased a project car and have been working on the engine. There seemes to be a question of is this engine a 260 or a 289. Per the vin number the car was manufactured with a 260 engine. How ever all repair components purchased were bought for a 289. The car is 45 years old and there have been a few hands working on it and not knowing if the engine is original or not is a question. The engine had valve covers and air cleaner that were some what grayish with a bronze over tone, this might indicate a 289. A 260 engine came from the fatory with blue valve covers and blue air cleaner. A 289 requires 5 quarts of oil and a 260 requires a little less than 4 1/2 quarts, this engine takes only 4 1/2 quarts. Spark plugs, valve cover gaskets, plug wires, ignition coil, belts and so on were purchased for a 289 and everything fits. There are numbers on the intake manifold but I do not know what they mean. If the engine were a 289 a (K) would appear some where on the block but where? Other than a complete tear down how can I make a identification that tells me I have a 260 or a 289 engine to work with. I would like to rebuild the engine and want to order parts but would like to drive it while I wait for the parts.