A couple of points here.
First, the pushrod angle changes as it goes through the lift cycle. The more lift, the more extreme the angle, so there is no magic number to plug into the trig formula. It is usually more than 11*, especially with a roller lifter.
Also, the sweep of the rocker would eat up some lift, but remember, the pushrod also sweeps, so it gets closer to the shaft centerline as it gets away from the perpendicular line at mid lift, so in theory that increases the ratio and offsets some of the losses at the valve. This is provided the rocker is properly designed, and most are not.
There is some sweep on the valve tip, but at .035" for .600"+ lift on a SBM, I'd say it's as good as it gets. It's the pushrod side that is almost impossible to correct, especially with that ball type adjuster. A roller rocker is a different animal, and the ball adjuster is a bad holdover from the stock design.
Also, the lash is not set on the pushrod side, it is on the valve side which has already accounted for the rocker ratio. You would not multiply the lash by the rocker ratio. It is as measured.
Looking at the dyno sheet, it looks like you have a bunch of reversion down low, killing the bottom end. Then the lobe separation and ICL is not letting the torque carry in the higher rpms, which is killing the horsepower.
Another observation is the improvement with only a half inch spacer. A larger spacer may have helped more, and it's likely due to airspeed being too high at the base of the carb for the air to turn and follow the roof of the intake port. It will shear off the turn there, just like the short turn in the cylinder head, if the airspeed is to high. There could also be turbulence under the carb choking off airflow as the mixture exits the throttle bores. A shear plate may help if that is the case.
JMO
