i own a shop, and I will try to make this clear to you. It can have either one in it. A second generation small block V-8 was introduced in 1992 as the 5.7 liter (350 ci) LT-1. Production of this second-generation design was subsequently expanded in 1994 to include a 4.3 (265 ci) version. Second-generation small blocks were installed only in specific production vehicles, the Corvette, Camaro, and the Caprice. The only way you can tell if it is the 5.7 is to get the letters off the front of the block on the passenger side just below the head. The information I gave you (above) is straight out of "Chevy Power" the official factory performance guide book #24502488. The deal is; they came with both the 4.3 and the 5.7, and apparently the only way to tell the difference is to go by either the numbers stamped on the top of the block on the drivers side just above the bell-housing, and/or the letters on the front of the block to be certain. I was under the impression the LS had the 350, but after reading this, I now know it can be either.
Glad to help out, Good Luck!!!