I thought 6.5's used DS4's?
Stock pump can do 70-75cc's max, maybe. Moose pump does 90cc's. The DB2/DB4 hybrid pumps can do much more, but are probably pretty spendy.
If I was to just get a pump that a stock turbo could handle, without wanting to go all custom, it would be a Moose or like pump. 90cc's of fuel isnt a lot, but it is certinaly enough to get anything done. In context, a stock OBS powerstrokes injectors are 90cc's, so a moose equiped truck should make as much (maybe slightly less) power than a chipped OBS on a hot setting with stock injectors.