Hello HMG25 and Welcome to the Forum;
Your question is an enginering problem. See if you can find a structural engineer on line and pose the question to him/her. There is much more information needed before they can give the answer. For instance the live load expected (snow), species of wood, bearing points, will the 2 X 8's rest on the beam or tie into the side of it, etc.
You may want to google it on Louisiana Pacific, Georgia Pacific or Warehauser web sites. I know what I would do but it may not work in your situation; I think you need professional help with this one.
I wish you the very best success with it.