can someone tell me how much approx. hp is lost from engine to rear wheels. I have a 350/330 hp engine. I have hearld everthing from 30 to 100 hp

What tranny and rear end?

The rule of thumb is 15% loss through the rear axle and this is arbitrary it could be slightly less or more depending on how play and or slippage your drivetrain has.So you have 330HP at the flexplate or flywheel 330X.15(15%)=49.50 loss in horsepower,net HP=280.5 .

running 700r4 non-electronic with 342 gears