How much hp in a GM Goodwrench 350 engine 10066036?

i have the same engineGM claims they got 310hp out of it with headersi got dynoed at just over 360hp with headers, electric fan, electic water pump and no other pulley driven devices it makes my 58 Chevy truck with the th400 bone the fuhg outonly thing i lack is traction

• Flattop aluminum pistons?....High nickel content?