CE BB number question?

[Mr70]

Do you mean Block#3999289?
The #289 Block was a 454 2-bolt main available from 1972-1978 on Chevelle-Corvette-Passenger-Monte Carlo & Trucks.What's the casting Date on the back of this Block?

If this is indeed a Sequence number,CE Sequence numbers are usually 6 digits.Are you Positive there are no more numbers on that pad,it seems to be missing one after the second 3.
*363 06=the first digit is the year,3 meaning 1973.
*63(?)06=would be a legitimate Sequence number from Tonawada plant in that time Frame.