Flaked grains with a high protein content - barley, oats, wheat - run the risk of throwing haze unless used in relatively small amounts. Less than 5% of the grist should make an flavor/mouthfeel impact without negatively impacting clarity.
If you're after "grainy", please rethink switching to 2-row. 6-row malt has a more "grainy" than "malty" flavor. It's slightly more astringent from elevated husk. Perhaps half 2-row and half 6-row...?
If you do go with 6-row, don't forget to reset your mill.