Hi Tedd, awesome find
i did some taper measuring a while back, and as fletcher indicates- there are some rough guidelines that will get you pretty close- my findings are very similar to his.
i find doing an 8" back taper wont lose much spine, and i find for every inch over 8" you lose approx 1# of spine.
like Fletcher said, this depends a lot on the starting shaft- but that should get you close.
I find on sitka spruce shafts, 11/32 to 5/16 over 8 or 9" will lose about 10 gr in mass
The poc is a bit heavier- so results may be a wee bit different, but maybe not too much.
there was a very good write up about why tapered shafts work so well, and how they improve performance significantly (especially a much quicker recovery from "paradox"), and its not just the inadvertent improvement in Foc, but the tapering has an even greater effect on the harmonics of a shaft, and plays the bigger role by far, anyway i will see if i can find the write up.