rocker arms

What is the main difference between stock 1.5 rocker arms and stock replacement Mopar performance 1.5 rocker arms? Are they better built, closer to 1.5 across the board as opposed to factory stock and finally are they worth the buy? Considering im not going with roller rockers ? I have a 77 318 with a 340 cam , four barrel intake and carb , 1.60, 1.88 valves eddy springs with other head work and headers also 9.1 compression . just trying to do the things dodge should have done if it were not for emissions standards of the time. Thanks for any input