the 4.3 is a 5.7 missing two cylinders. I myself built a 300hp version for a friends Blazer (although it was a bit tempermental). GM has 400hp versions that they ran on the Salt Flats.
They respond just like any SBC with the same bolt-ons. They just make 3/4 of the power.
I myself like the engine over the 60 degree V6's. The 96 and newer with the Vortec heads were rated at 190hp which is plenty for a truck
