I thought Simcoe had a "piney" aroma/flavor... And Kolsch shouldn't really have any huge hop flavor or aroma from what I understand. I'd think the 2oz of Hallertau (depending on the AA%) should be it in my opinion.
I think at a certain point, it doesn't have any business being called a Kolsch when you play with the adjuncts (assuming you're using honey) and hop varieties and schedules. But that's the purist in me I guess.