Thought I would share:
I made a R/D bow for a friend in the low 40's.  He has a long draw and what was suggested for him were the GT 55/75's.  Skeptical of how they would work he purchased an half dozen and left them for me to assemble, which I did.  Then I picked up my bow, a 50# Martin Model 10 Pioneer, to shoot and grabbed one of his arrows along with my 35/55's I normally use.  To my surprise the longer stiffer arrow shot even better than mine did.  Today I grabed 6 of mine and the 6 of his to see if it was a fluke.  Nope.  For a center cut bow the stiffer spine didn't make a bit of difference for me.  Very smooth shooting arrows.  
I would have never guessed.

If his arrows are longer that will weaken the spine and depending on how much weight is up front will make them even weaker. They may be close in spine after you added the points. I usually get mine a tad heavy and shoot 250-300 grains up front. Just becasue i like heavy arrows. If i ordered the correct spine and added that much weight i would be way to weak to get good flight.

They are longer but still the same tip weight up front, 125 grains.  I would love to know how they respond to my 250 grain BH's, though.

The closer a bow is cut to center or past center, the less sensitive it is to spine.  Or, put another way, the wider the range and the higher the spine they'll shoot.

I have slowly been adding weight up front, I am wondering if I need to change arrows. I shoot 55-57 lb. longbow, not exactly center cut, GT 5575 with 200 gr. up front, thinking of going to 260 for head weight, Arrows are full length, 33"
Any thoughts, what do you long drawers shoot?