I checked on my take off barrel, at 9" from the receiver there is a mark from the original SA band, I think. I tried the 1/2 wide aluminum "nut" and the band can be forced to that point, I am fairly certain the band will pull to fit the barrel there. The depth of the pocket under the barrel is a little than 7/16 and still needs to be about .7inches wide. The barrel is .728 at that point so the recess will need to be made for .778 wide to accommodate the barrel plus band thickness. Other than the recess for the band thickness nothing out of the way will show from the barrel side.
So on the barrel side you need a rectangular pocket .778 wide and 1/2 long and almost 1/2 deep. If I was doing it, I would use a piloted 1/2 drill to rough the pocket and put the corners in with a Dremmel type tool. For the escutcheon recess possibly use the same drill to make a pocket 1/2 diameter and 1/8 to 3/16 deep. If you have at least 1/4 left for the escutcheon to pull against it should not cave in the stock at that point. So is you stock about 1 inch or more thick at 9 inches? That will be the what you would measure with you calipers (top of the barrel to the bottom of the stock) minus the barrel thickness.
LocalBoy's application of the original SA band looked real professional, I am not sure if I could pull that off myself. I think I could buy a couple of hard ware store 1/2 paddle drills and make the 2 pockets easy enough. I need to go buy one but I am thinking of sharpening the shank side into a cutting edge and pulling the drill through the centered pilot hole.