Adding 2.02 intake to J heads

Question. Would having 2.02 intakes be beneficial to have added the 1.88 J heads on a street car? When I upgrade the cam soon, I was thinking of putting 2.02's in. I have heard that it will not be beneficial if the motor is not seeing a consistent 4000 rpm and also that it will lose bottom end. I also heard that it can add up to 20ish HP across the board. I am upgrading the 360 soon with the Xtreme 268 cam, speed pro flat-tops and 3.91's in the rear. I have less than 1,000 miles on the heads and if it doesn't give significant gains, i'll skip it.
Thanks for your thoughts!