Get the PHS docs for that VIN for starters. Trace your VIN no. back as far as you can (original bill of sale, pink cards, previous owner. You know where both hidden VINs are? Is you engine nos. matching? Did you match the VIN on the engine?
Do you have a rare 69 car other than a 400 vert?
Engine Test Stand Playlist: https://www.youtube.com/playlist?list=PLwoxyUwptUcdqEb-o2ArqyiUaHW0G_C88 restoring my 1968 Firebird 400 HO convertible (Firedawg) 1965 Pontiac Catalina Safari Wagon 389 TriPower (Catwagon) 1999 JD AWS LX Lawn tractor 17hp (my daily driver) 2006 Sequoia 2017 Murano (wife's car) 202? Electric car 203? 68 Firebird /w electric engine 2007 Bayliner 175 runabout /w 3.0L Mercuiser__________________________________________________________