I think what you have is 1401544, which is a 454 used in 1975-87 trucks. It is a four bolt main and should be a good basis for building a stout street engine for your Chevelle. I always like the 70 body and the SS454 was definitely one of the really great muscle cars of of that era.

If nothing else, you can install the engine and drive it for a while and see if you like what it does in it's stock configuration. Easy changes would include intake manifold, carb, and headers. There are several bib block wizards on this site that will have a lot of great information if you're up to some serious building.

Have fun,
Glenn