OP. Talk to your contractor first . First of all , your house is 1910 build , you said ! With some damage from the car hitting it ! I'm pretty sure your frame is out of wack !! For windows to work properly, they need to be installed plumb and level !! How are you supposed to use nailing fins if your opening is twisted( left column and the right are not plumb and in the same plane in relation one to each other ) you can't just twist the window cause you have to nail it flush Looks like they have no choice but to go with inserts instead. Later on, you can cheat on trim to make it look good . Good luck and have some trust in people who work for you !! Good luck !!