Have you measured the diameter of the wire used to make the spring? From that you can determine the weight.
I'll be surprised if it's as lite as 14lbs. The commander spring was originally just a stock full size spring cut back 5 or 5.5 (as I recall) turns to prevent it from getting fully compressed, with your size collection you surely have spares you could play with.
You could fit a larger radius firing pin stop, that will reduce the effort required to rack the slide. Same with a reduced weight mainspring.
Have you tried cocking it manually and then racking it? Compare the effort required to your other 1911's and that will give you some insight into how changing the recoil spring will affect the effort required.
Finally, you've spent how much time trying to get someone to give you a more specific answer, why not just order a 14? It's the lighter of the factory recommended springs and if you happen to have one installed then you'll have a spare, and if you have a 16 installed then you get to try the lighter spring. If you have lots of free time call Smith back and ask for one, they'll probably give it to you to get you off the phone, otherwise Wolff is your answer.
Good luck!