If it was cast early enough, it would be a Hemi block destined for NASCAR; after that it might be sent to a NASCAR or a drag racer. After that, say mid-'65, it could have been destined for NASCAR, drag racing, or Street Hemi production.
The earliest blocks (late '63 to very early '64) had strength problems that were solved very close to the Daytona race.
I'm pretty sure all Hemi blocks were created equal once the early issues were resolved, but if there's a way to authenticate some race-shop engine-builder's stampings or modifications, that would make it a cooler piece than the one in my car...