With a cam that big, you will probably make less power than with a standard cam because the overlap is so huge, the exhaust pressure will cause reversion(going backwards)into the cylinders.
I built a 440 once & used a cam with only 234/244@050 & .480 & .510 lift with standard exhaust manifolds. It went 14:00@ 102 mph & next meeting I turned up with some 1"-7/8" headers & straight off run 13:00@113mph. This was pushing 4000lbs.
Unless you run a mild cam, toss the manifolds.
Mike in New Zealand.