I am running a 472 caddy comp cam stock heads vortec springs alum intake 355 rear gears 2850 lb car,400 tranny 2000 stall cheap rebuild on it rings and bearings runs 12.5s in the 1/4 all day leaving it in drive . They are a tough big torque engine as long as you dont over rev them 5000 rpm is the max you should spin them and want them to last