All I can say is not very much, I found the best way to confirm the cavity is fully primed, is to leave out the top pin security bolt, and fill through the nipple with a small grease gun filled with the oil, one air has escaped and pure oil comes out, all is good.
Since I think the holes in the shaft are at the top...wouldn't it make sense to juice it good till it leaks and then let it adjust to it's own level...half a shaft full of oil, won't get to the bearings...or? Correct me if I'm incorrect on this, as my next project in just that....swing arm and its' leaks.... :wink:
If you work it out the 750 should take a minimum 84cc (1/2" bore x 7") + drillings and area at the end of the caps/pin. The shorter 850 a bit less.
the others are right... fill till it bleeds out the top hole. I'm amazed where it goes, put a new pin in 2500m ago, filled it right up and other than a little weepage past the seals there was no real mess but when I stripped the arm out to sort the frame alignment there was only a few cc left. Mine is a good fit with little end play and good surfaces for the "O" rings to run on. I guess the bushes absorb some but not that much....