Please help authenticate this L78!!!

[Mr. Duece]

I have found wht is "believed to be" a 68 Chevelle SS L78 car. This is a 3 owner car with 25k original miles. I spoke with 2 of the 3 owners who verify this. I'm still looking for the original owner. The interior has never been removed nor has anyone ever looked for a build sheet. Beside the 6500rpm factory tach and single 3/8 fuel line, is there anything else I can look for? This car is Grotto Blue/Black 4 speed, 488 12 bolt. Also what is the difference between the K8 and KO coded rear end housing and could you get this housing in another model other than an L78? Any help would be appreciated as I would like this car in my garage next week. Thanks, Don