Instead of swapping the rockers, I'd swap the cam. With the SBC you have a world of choices, including economy cams. An econo cam would not only change the lift, but also the timing and duration. That way, your whole valve train would be tuned for economy, instead of just changing the intake lift.
I wish I had as many cam choices for my Cavalier. My only options seem to be stock, two racing profiles, or a custom grind.
I think I'll just advance the stock cam 5 or 6 degrees, and call it good.