Rocker pushrod geometry method

Has anyone seen this video and if so is the method accurate for setting Rocker arm geometry and pushrod length??

https://youtu.be/o5is9BsH5OU

https://www.460ford.com/forum/37-engine-tech/199314-some-technical-help-you-guys-building-engine.html

TommyK wrote:https://www.460ford.com/forum/37-engine-tech/199314-some-technical-help-you-guys-building-engine.html

It does work most of the time.  Sometimes the pushrod angularity can be way off but, that usually means that the rocker arm itself is way off for use with that particular application.
The pushrod/rocker arm junction is the highest loaded area in the entire valve train system.

I used this method last night on my new motor build and found that it got me very close but using the eyeball to draw the straight line on the rocker, then using the eyeball to set the line parallel to a straight edge does leave room for some variation.
By just using the described method, I thought an 8.750 rod would be the ticket on the first pass, then I did it again on another cylinder and my official eyeball must have had a different alignment because it gave me a measured length of 8.791.
So, I scribbled black sharpie on the valve tips of #1 and #4 then rolled the motor over 3 cycles with the adjustable push rods set at 8.750 and again at 8.800 and found the 8.800 pattern was centered on the valve. and the 8.750 was a little high.

Now I can check valve to piston clearance. IF that checks out, I can get the push rods ordered, and if I have to go with a thicker gasket, then I'll measure for rod length again.

Thanks
Alan