i have a 2 door wide closet door opening (was 2 bi-folds) that i would like to install a pocket door into to regain some wall. this is the existing opening (73 1/2" W x 80 3/4" H rough opening): and this is what i want to do: the problem is that according to the millwork guys at Lowes and Home Depot, the pocket door frame requires a 85" H rough opening. since i don't want to open the wall above the door and raise the header (1 2x4, non-load bearing) is there any reason why i can't just remove 4" from the bottom of the frame and door to make it fit the existing opening? also, this is a slab foundation, how to i attach the pocket frame to the slab? liquid nails or some other adhesive? small L-brackets screwed to the frame and concrete?