Help with 1968 GT500 Restoration

[Nubs68]

I am helping a friend collect some parts for his 1968 GT500. I found this motor in the back of a garage while looking for some Chevy Parts. The owner did not know the history of it as it was his father's (who passed away). I bought on a hunch and quick inspection. The Block casting is C7ME-A with a bore of around 4.13. This should be a 428 Block. The heads are casting C8AE-H with 14 bolt exhaust pattern. It has what looks to be an old Edelbrock aluminum intake. Is there anyway to tell if this could be a "Correct" 428 engine for his 68 GT500. The original engine is long gone from the Mustang. He wants to put it back as correct as possible. Did they put the Police Intercepter 428 in the GT500 prior to the release of the Cobra Jet version? Any help would be appreciated.

Matt