In my vanilla porter, I use like 2# of Munich. Also, do some c40 and c120.
I'm personally not a fan of 90 minute hop additions so I would just up them and do it at 60, but that's just a personal preference.
Having brewed my vanilla porter a few times, I'd highly recommend using two vanilla beans and adding them after primary fermentation instead of during the boil.
On Tap: Amber Ale, Pumpkin Ale, Rye IPA, Wee Heavy, Apfelwein
Kegged: Barleywine, RIS, JD Barrel Barleywine, Bourbon Oaked Porter, Belgian Brown