olds 455 Rocket engine ID

[John]

Okay all you Oldsmobile guys...I need your help in identifing what I have here.
...a friend pulled this motor out of a street rod and says
"It is a 1970 455 Rocket motor..with turbo 400 , holley 750 carb."
It has what appears to me to be aftermarket "oldsmobile" aluminum valve covers" and "offenhauser 360" aluminum intake.
....numbers on the carburator are:
4777-4
0805
...
...block casting is # 396021F
...head casting is #cfd 394 648 313
...it has a silver with red copy round metal piece on the air cleaner that says "OLDSMOBILE 455 ROCKET"
... Where would I find the casting date on the block?
... Can you tell from this info what horse power this motor is?
...The motor is on a stand so I can get photos if they will help....thanks