There are a couple of options. Marcel Massini, international Ferrari walking encyclopedia, will have records. The original importer (if you know the country of original delivery) will likely also have records. You can also register as a Ferrari owner with the factory and they can also provide you with records through the website, I believe.
My pleasure. On the value, depends on who you talk to. Pesonally condition would be much more important than if it is the original color.
Most Dino's were repainted in red to increase their value. But I do think there is a slowly increasing number of people, although still in the minority, that prefer the car to be in its original colour. Mind you, there were some horrible colour combination in the early Seventies...!
I am restoring a1974 Dino 246 GTS. Contact Piero Navarro at www.modexotics.com. If you give him your vin number, he should be able to track it down for you. He also has access to parts and will answer your questions for free. He also restored my 1984 Boxer 512BBi as well as a dozen other exotics.