97 Votec 5.7 HP

I have a '97 Z71 Silverado with a 5.7 liter vortec 350 and I would like to know what the HP rating is on this motor. Also my brother has a '99 short wheel base with a 4.3 liter and we were wondering what the HP was on that. He has a 5 speed standered and its 4 wheel drive what should he expect for gas mileage? Thanks anyone

The silverado is under rated at 255hp, most people think closer to around 280 hp, and the 4.3L is 190 hp. Not sure on gas mileage tho