im thinking about trying some carbons but I dont know what spine I need. Im shooting a bear Grizzly 45@28 and I pull 28 1/4. Im either gonna get Carbon express predators or Beman ICS bowhunters  since moneys tight right now. I would like to shoot around 250 grain point weight. If someone could tell me what spine/point weight combo should get me close it would be greatly appreciated

I would use Stu's calculator and play around with different set-ups.  It will get you darn close.

Does such a calculator like Stu's work for tapered shafts like GrizzlySticks or AD Hammerhead's?

No, I believe they/he states somewhere it is for parallel shafts only.

i had some tradtional only arrows they were 400s with 100gr brass inserts and 165gr broad heads they shot real good they were just real heavy