Mastering / Critical listening room

Hello all, Firstly thanks to those responsible for the great resource. This is my first post and first attempt at using sketchup. Here's what I am designing: A critical listening room for Mastering and some ITB mixing. The room is in a basement in the middle of nowhere so outside isolation needs are minimal. This will be a diy project with between $2-3K usd budgeted for materials + much sweat equity. I have attached a Sketchup overview of the elements in place and my rough view of the layout. The ceiling is currently stuccoed sheetrock on 2x8 joists. I am considering tearing it out and going with 703 behind textile and wood slats. The three walls opposite from the brick wall are partially covered with rough sawn pine boards and batten running vertically. I was hoping to reuse some of this with dense fiberglass between the studs and textile over the rest. I will obviously need some absorption on the brick chimney behind the listening position. There is a beam that is exposed below the ceiling which bisected the room. Dims are 4" w x 12" d. I'm sure some bass traps are in order. I am building this room primarily around Dunlavy SC IV'a for the main monitoring source, plus some small powered nearfields for mixing ( Dyn BM6A's). All information I have read on the the Dunlavy's is that they perform much better on the long wall, thus my rational for the orientation the way I have drawn it. I tried to make the drawing show the tabla rasa as it were, just the imutable parts of the room. All the other surfaces are open to whatever needs to be done with them. thanks for any guidance you can give me, trin

If I were in your shoes, my placement of the speakers would be on the wall to the right of where they are currently in this picture. This is common positioning as it relates to suggestions here @JLS, so the speakers can fire down the longest length of the room. Ymmv, the search function does work and good luck with your project, Brien