Looking for advice input on what options I have for insulating the exterior walls on a block house I have in NE lower Michigan. Exterior is vinyl sided with I believe some type of insulating board behind the vinyl, think celotex or some similar type product. Interior is shown below. Firring strip on the block that was covered with a reflective paper then paneling. We are looking to remove all the paneling and have these walls drywalled. Right now I am leaning toward doubling up the fir strip after covering it with a vapor barrier and then using rigid foam. Thoughts?