just picked up a 383 stroker from a friend but i want to change the cam to a hydrolic roller and a smoother idle the cam installed now is .507 lift 235in 285 ex the 383 has dart heads with 76cc and 1.5 rockers

around 110-112 LSA, 480 lift, 232-4@.050, 1.6's on the intake
oughta pull plenty hard for you without so much lope.

Try a Competition Magnum Cam and Lifters Set. I have the Magnum 270 Hydraulic Cam and the car pulld hard with a fairly smooth idle.

I went with an Isky roller with the following in my 383:
@050 225INT\225exh w/ 108 lobe .505 lift

i will want to pull enough vacume for power brakes

i will want to pull enough vacume for power brakes

At worst you can always add a vacuum reservoir and only run a 9" booster.

i will want to pull enough vacume for power brakes

Run a wider LSA like I suggested earlier.

Which Dart heads?

depends on how you drive the car. 200CFM is usually the choice.