Welcome to the Team Nathan!
Keep in mind that today's pump gas is knocking the power potential of a big block into the dirt. You have to go big with a big block to make the same power as a small block on 87 octane, so you need to think a 496 as being a good start. Looks like a 396 or 427 (and it is just as heavy), but it will make 425 horsepower just like the 409 425 horse big block did back in the day (or a 425 horse 427 for that mater).
The decal you stick on top determines what motor it has for most people (that is why I labled my 582 big block as a 402).