Well here it is less the 1/4-28 tapped hole. To get this in the stock it will need a pocket 15/16 wide, 9/16 length wise (parallel to the barrel) and 1/2 deep from the bottom of the barrel channel. I think a 1/8 thick washer inletted into the stock would do. Between this washer and the bottom of the 1/2 deep hole I think 3/16 of wood would suffice.
So from the bottom of the barrel channel to the bottom of the stock 13/16 minimum. the photo is showing the band at 12.5 inches from the receiver, at 10 inches there is some obvious distortion in the band but I am sure tension would pull it flush with the barrel all round.
With B/R's suggestion that the screw also hold the sling swivel a little more thought would have to go into this.
Stock work would need to involve drilling a 1/4 inch hole through the center of the barrel channel. I would use some sort of piloted drill to make a 1/2 pocket from the top and maybe a 7/8 pocket from the bottom. The pocket in the barrel channel would get the rectangle shape 1/2 deep with a Dremel tool. Make a countersunk 7/8 washer for the bottom and screw it in.

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