The stock 3.4 is rated 160 hp / 190 ft.lbs,207 cu. in. With increased induction [bigger carb or tbi ] freeflow exhaust,cold air intake,175 / 180 hp / with 272 cam and pocket ported heads,200 hp ? I ve had much more expirence with the sbc than the 660 but it's not hard to make a hp per cu in with stock heads on a sb. Hedders for 2.8 ,year and model of your truck.