Max lift with stock valve length?

For example...

230seat/580open on a .660 net lift street roller cam (2.14I/1.81E, 1.5 rocker) 6500rpm max engine speed

280 seat/720 open on a .740 net lift endurance roller cam (2.20/1.81, 1.7 rocker) 7500rpm max engine speed

Would really like to know where data like this comes from? Your own testing, or..? I’ve tried searching for specifics like this and apparently don’t know how to Google. Maybe there’s a calc or software package for it? I know the old lb/.001” lift rule of thumb (basically what my cam came with from comp), but would love something more accurate, especially when using the thinner wire with higher frequencies and such. Thanks!