your cam is too small, use a 750 double pumper. what size primary tubes on the headers? a mild 330 horse 350 is going to have higher torque figures that engine is doing what it should with those parts.
usually if you use 1.7 rockers on a small block,the stud needs to be relocated.
your cam needs more duration more than more lift.use a cam that allows 6200 rpm and the hp will rise