A .500" valve (not cam) lift with a true 1.5 rocker, would have .3333---" cam lobe lift. Because of the lifter angle, the trig function shows the cam lift seen at the rocker to be .3234---", which would make the valve lift .485". The bigger the lobe lift, the more loss and a smaller lobe is obviously less loss. The rocker ratio will have no effect on the amount of loss if the rocker geometry is correct, i.e. correct pushrod length on a magnum and correct shaft height on the LA. Fwiw, the lifter/pushrod angle is not as problematic as it would seem.
If you were looking to get 1.6 at the valve, you should have kept the 1.65's. You would have been a lot closer.