Geeze I'm slippin...forgot to mention if it is a 406 service block it would have a 4.13 std bore like the 428 had. Also the C4AE-A 427 would have the "HP" markings by the casting number. The std 406 casting numbers are...
C2AE-J
C2AE-K
C2AE-V
C2AE-BD- also crossbolted
C3AE-D
C3AE-V
Also is the block set up for solid or hyd cam?
G.