Okay then, for all the carbon guru's out there:
I'm shooting a Bear Montana longbow with a 64 pound draw weight at 30 inches. My arrows are CX Terminator Hunter 6075's that are 31 inches long. About how much weight do I need on the end to get them flying well?

Get you some different sizes of field tips.  
3 rivers has a field tip test kit?

I'm also shooting a Montana, but 55# at 28".  My bow shoots best with CX Heritage 350's cut to 31".  It shoots good with 125gr tips, but better with 160 gr tips.
Good luck!

125 should work well.