Live in Zone 5b, going to shoot for 2" of XPS DOW foam board. Planning on gluing it to the concrete wall with foam board glue and bracing it while it cures. It will run to either the top edge of concrete or to the I-Joist and then have spray foam behind it to fill the void between P.T. sill plate and the back side of the XPS foam. Taping the vertical seams. Then going to run 1x4 (since 1x3 isn't available locally) horizontally and use ramset w/ washer or tapcon screws or a mix of both to secure the 1x4 on 24" centers. I don't like how short the ramset nails come in. Then going to run 1x4's vertically on 16 or 24" centers that screw into the horizontal 1x4's. Then going to run wire, and drywall in those steps. Considering cutting puzzle pieces of 1.5" XPS to place in the grid I create but that's not for sure.
What am I missing, if anything?