Engine identification help needed

[entropy454]

This picture is from an engine of a 1967 vette. It is claimed to be a 427 but I am having trobule identifying the numbers. Also I noticed some of the stamp seems to be backwards. Any idea what that would mean?
It looks like it says :
TI21bIL 710684

http://s368.photobucket.com/albums/oo121/swainal/?action=view&current=3a46_3.jpg

 

[Vettehead Mikey]

This is an engine assembled at Tonawanda NY on December 16th and originally installed in a 427/390 Corvette, serial number 10684.

It's normal for the big blocks to have the position of the stamps reversed from a SNC.