Injecter PW vs HP vs RPM

Tell me if this is bad info
Maximum injector on time.
rpm dependent.
formula- 60000/rpm x 2 = max on time.
60 ms is 100% at 2000rpm
30 ms is 100% at 4000rpm
20 ms is 100% at 6000rpm
15 ms is 100% at 8000rpm
https://www.stealth316.com/2-calc-idc.htm <--- anyone have this as an excel sheet?

Street should be held to 80%
Short duration should be held to 90%
If you wanted to size an injector to a vehicle would you start with Horsepower as your base and lbs as your variable?
Lets say you have a relatively stock non E85 injector-ed vehicle. You put on headers, a modest to big cam, Cold Air intake, better exhaust, maybe larger TB.
What would you calculate the needed lb injector? Guess based on experience? Guess and a WOT while recording ms? Some spread sheet? A calculated range based on HP?
Thanks in advance.
Danny

You're on the right track.
It's pretty easy to calculate the proper injector size if you know the target hp and the BSFC.
Here's a link to Wallace Racing Calculator's site. It's pretty handy to get you in the ballpark.
http://wallaceracing.com/injector-sizing.php