Frame around duct work and beam
I am wondering what would be the best way to frame around the ductwork and beam that I have in my basement. The first picture is a photo showing the ductwork and beam. In the middle of the two, there are copper lines, conduits, and a 4" main house sewer drain. Photo two shows a few sketches, the first sketch is calling everything out with dimensions, sketch two is showing approximately what I would like to do, sketch 3 is left blank in case you wanted to make your own sketch of what I should/could do. Edge of beam to edge of duct is about 3'-7".
Is using ripped 2x4's with 1/2" plywood ok, or should I got with a mini 2x4 wall everywhere? I know its non structural, it only has to support the weight of the drywall. I used the 2x4 wall on the side of the duct to help give it rigidity, since it will be spanning a farther distance.
With the way I show it now, the drywall has to span 2+ feet, I am worried the drywall would sag in that area. Can I use steel studs, are there products out there to help with this scenario, to help keep head room loss to a minimum?
I am trying to keep the most headroom I can. Right now, from floor to bottom of beam is 6'-7". If i put the drywall right underneath the beam, that would lose me about another 1/2". But that means the drywall would be right underneath the ductwork too then. The ductwork is only 1/2" higher up then the bottom of beam. Notice as the ductwork gets further down the line, it gets smaller, that part will be easy to frame around, because I can run horizontal 2x4's to help support the drywall. If I want to do this by the bigger trunk, i lose even more headroom.
Any info or advice would be great.