If it was ordered with a 427 it would be a COPO car, search that. what kind of tell-tale signs. The original owner is going to be your best source, he should be able to remember where the original parts went, He should have some old pictures. Ask him what month he bought it as compaired to the build date. What are the numbers on the rear end? Post pictures. does the VIN number have an L or a N in it? Dana chevrolet also sold regular family cars, factory Hi-perf cars and trucks. good luck, you never know.