If RAS rebuilt and bushed them, they should be closer to advertised than OEM. But with all the variables, including the OEM lifter and pushrod angles, a true 1.5 rocker will still not give 100% of the advertised lift. If you need a precise lift, you would need to go a little bit over on the rocker ratio or a little bit over on the cam lift to make up for the less than optimum geometry.

Either way, you would need to do a lot of measuring making sure to have the lifter pushrod cup is in the exact same location as the lifters you're using. Hydraulics will collapse a bit and using a different pushrod cup height and/or different length pushrod will throw off the measurements.