Measuring For Pushrods...mid-lift Method Or Not?

You can use any method you want. What I do is keep adjusting the push rod in .050 increments until that gives maximum lift at the valve. I have the dial indicator on the valve. Before I start I have already checked what the lift was at the lifter. So with that number and the rocker ratio you can calculate the theoretrical lift at the valve. I have a Proform valve checker kit that makes this really easy that I bought years ago. Once you are finished check your scrub at the valve and adjust as necessary. It's all about kintimatics.

Without getting to deep mid lift does can get you there. I have found it to be ineffective on high lift big spring pressure as you end up with poor geometry at 0 and max lift and ideal at mid lift. What this causes at high lift is push rod deflection/adjuster or rocker failure on the push rod end.

I used this method for my most recent build, worked out great.
In the video they used lightweight check springs but I did not and was able
to get correct results.
View: https://www.youtube.com/watch?v=o5is9BsH5OU

Gasket thickness would be accounted for if head is torqued. I used this method when assembling my
engine on the stand and just snugged the heads. I also did it with engine installed and heads torqued
when I changed rockers, worked well in both applications.

I checked one for reference and it looked good so I proceeded with the rest,
When I changed rockers used the same method and didn't bother with the marker check.