I just ran the numbers through the 3 Rivers calculator and it says a 29" 1535 with 125gr point would be way stiff for even a 28" draw, let alone a 26.5" draw. I don't normally use the 3Rivers calculator, so maybe I'm doing something wrong. (I use Stu's original calculator, but I believe he developed the one for 3Rivers).
There are so many variables such as string,(I used B50 for string) and strike plate thickness (I used .06 for an approximation of velcro). I'm not surprised we get different results, but I would sure start with a full length arrow and cut back VERY slowly. I will bet it never gets back to 29" before becoming stiff, though.
I'm shooting 30.5" 1535s with either 145 or 175gr points from 43 - 46# bows drawn 28" and bareshaft and fletched fly really well together. When I put these values into the 3River's calculator, it comes much closer to matching, depending of course on the variables we don't know.
I notice Dutchman is also using 30.5" full length 1535s, but drawing his to 29", so it sounds like 125gr points are about right for him. And we're both using fast flight strings.