We recently purchased a home and this window was boarded up on both sides. I removed the plywood to discover that it used to be a old coal chute. I removed all the old fiberglass insulation that was in there but I am at a loss on how to frame this to install a window. I know I need to finish removing the partially busted concrete on the left and right but I dont know how I would secure some pressure treated wood to frame the bottom.
Option 1 - tapcon screws (or similar) into the solid parts of the block.
Option 2 - stuff some wire mesh a few inches down the holes. Mix a very stiff mortar/concrete, place on top of the mesh, make a lovely smooth flat surface, and drop in some anchor bolts (probably overkill for a windowframe) or just screw the board in with tapcons or the like but without having to hit the webs since you'll now have solid masonry.
Option 2.5 (modern) - sprayfoam (great stuff or similar polyurethane foam) the holes, then put your concrete/mortar on top of the sprayfoam.