I'm going GSR
I have both so I have room to play... An LS in my car right now and a GSR in the garage(complete SWAP)
I rather give up 3 or 4 hp and lb of tq and be able to rev higher and have a piece of mind... since I'm going with cast iron pistons and stocks rods... and I have some pretty big cams that make power to about 9 9.5 k