the taper
A purpleheart shaft should get the job done without breaking the bank. I would think a bit faster taper than a pro taper, say 1.5 or 2 mm per foot. That might cause you to have a little smaller tip than a 13mm when you calculate the thickness in your bridge. Comparing the thickness to the thickness of your current shafts might also indicate you won't have a problem, just one thing to check.
One thing you definitely want is a parabolic taper. Which is just to say an "S" curve instead of a simple curve where you transition from the taper of your butt to the taper under your bridge hand.
Don't have a longer than you need taper from the tip, bringing the parabolic section down just a couple inches can make a big difference.
Very small changes in a shaft profile make a big difference in how the shaft performs. I spent over a month and snapped a lot of blanks until I got "my" shaft profile. No doubt plenty more similar but this one is mine.
Hu
