1922 Home bathroom remodel

I have a brick wall (uninsulated) exposed in the bathroom. I am replacing the tub and installing a wall surround. My plan is to paint the brick 2-3 layers for sealing, then put up plastic sheeting and furring strips. Next plan to put up blue board insulation boards, but unsure what to put up as the "innermost" wallboard. The tub surround will cover all down at level, but will probably just be painting above for now. Any ideas on the best type of board to use. Also concerned about the weight of the installation board but will work with what I have to. Thanks for any feedback, D