First, congrats on a great gun. You are right the .695 will not give great patterns. The #4 will likely not be very good and you won't be happy. The number 5 depending on the load may be good, but I would at least go down to #6 to really get the numbers you want. You don't need to go to the heavier than lead loads, but a change to #6 will improve patterns greatly.
The IC is a great choke in the MB, and I shoot one. I shoot an open .710 b/c I shoot handloads that can really be choked tight. I like more open for hunting. The .675 will serve you well no matter what load you choose.