@oakhollow Thanks for reaching out!
I took a look at the Freedom Bib Snow Pants and the Freedom Snow Pants from The North Face for you. As someone who wears 40 inch waist and 32 inch inseam, I would recommend going with an XL. I was able to easily put on an XXL pair of the Freedom Snow Pants over a pair of pretty baggy jeans, so I believe that would be too large for you. Additionally, the bibs are a bit more forgiving in the waist than the pants, so an XL is likely the right size.
The main issue for you could be the inseam length. We carry the pants in a tall size (34" inseam) but, unfortunately, we do not carry the bibs in a tall. The North Face does make them in a tall size, so we could facilitate a special order at your local REI store if you would like to order them through REI (subject to availability). I did find the pants, at an inseam of 32", to be pretty long even though they were my size. They are a pretty baggy style so the 32" inseam may work for you, particularly with ski or snowboard boots on. I am 6' tall with a 32" inseam, for reference.
I hope this helps, have a great day!