Rocker arm help needed

Im nearing completion of my 306 build but need some help. I want to swap over my stock stamped rockers from my old heads to my new gt40 heads. is it as simple as unbolting them and putting them on the new heads, and torqueing down to spec? is it possible to do this with the heads off of the car or must the new heads be bolted down with the pushrods installed on the block?

torque down to how many ft. lbs? and also is it ok to re-use the lifters if they aren't put back in the same order as before? i'm also using my old cam.