Road Runner Nest

I have 4006630-440-7 stamped on my block what does the "7"stand for?
It has 452 heads W/small Tapered spark plugs.Date Stamp of 3-17-76 What do i have?

I believe it's a date code. 7= 1977. That casting was used from 75-79. The 452 casting #4006452 used between 76-78 400 and 440's 2.08 intake and 1.74 exhaust valve.