block identification concern

Block date is 1 27 1973.

It probable a 413 or 440 industrial.
If so those are thick cast blocks. So if you want to go 60 over on a 440 that's the block to do it with. Or if it's the 413 you can punch it out to the 426 wedge with no problem.
If you replace the heads with standard car heads you would have about 6 to 1 compression ratio but then you could always put a supercharger on it then.