I should of posted this a while ago.
I've spoken to a guy who used to be head of the design department , at hamilton jet working on the inlet manifolds for the v6. In his opion the factory manifolds are not good. he suggested rasing the carb. With regard to which carb he thinks the 38 weber is good for about 180bhp. As he said to me all his work was for boats so the desired torque curve was different. But the overal out come is about the same. He suggested port polish and a tickle of the cam.
I guess as with all old manifolds the casting is super tidy so port and polish should open up plenty of power. Apparently Hamiltions did it to all thier motors.