How to ID 1968 SS or Z28 camaro??

[Big Squeeze]

I'm sure this has been asked a million times, but I've done a search and haven't found anything......

I've got a customer that just bought a '68 Camaro from one of her good friends that's had the car since at least the mid 80's....It's been repainted once.....engine has been rebuilt at least once......has an SS hood.....11/16 front sway bar........3.08ish open diff 12 bolt.......multi-leaf leaf springs......console with gauges.....in dash factory tach......4-speed......."350" emblems right at the front of the fenders......."SS" right below the "Camaro" script on the fenders right in front of the doors........so, I'm trying to figure out what this car started life as......Where do I start?? Does the VIN number tell anything? Tag on the firewall tell anything?? any way to do a background paper trail check??

Thanks,