300 series arrow are pretty stiff for any 65 lb. bow. Most charts would suggest that, with 100 gr. heads,you would shoot a 340 series if the shafts are left longer (29"); and even a 400 series if the arrow was fairly short. 65 lbs, for archers with normal draw lengths, is kind of a teetering point between the 340 and 400 Easton shafts. Go down about three pounds and you are spot on for a 400 series, or go up about three pounds for the 340's. You can obviously cut the shafts shorter to increase stiffness, or increase head weight to decrease shaft stiffness.

With your shafts cut to over 30", I would suspect there is quite a bit of arrow hanging past your Whisker Biscuit. This doesn't hurt anything - other making the arrow a little heavier than a short one - and in your case makes the overly stiff shaft more flexible. So I wouldn't cut it. And I would think about cranking the bow up to 70 lbs and/or going to 125 gr heads to try to mitigate the fact that you bought too stiff of an arrow in the first place.