as suggested above,, about 400 grains on each limb should be enough,, you can weigh the deer tendons whole and get an idea how many it will take,, I have weighed the elk tendon whole and then processed it,, and it is close,, you loose a little to waste when you separate it to threads,,
for best performance, you want least sinew to hold the most reflex,,
1 oz is about 420grains,, I guess you could put 2 oz on each limb on a bow that long,, but it does seem like alot,,,