You don't state what actually "blew up" on your existing engine. (you may not know at this point) However, I agree that you can get a factory rebuilt GM quality "crate motor" at a considerable discount from GM without necessarily going through the local GM dealer at retail price. You have to decide if you want to take the chance of having an "indy" technician/mechanic install it because if they don't buy the engine (from GM and add their own markup) they will be working for you by the hour. (no materials guarantee, just labor) Good luck to you.
Chum lee