Little change of plans. I decided to go back and use the original magazine tube because it was thicker and fit better. It also didn't have the screw relief notch in the wrong place. The only problem was filing out all the pipe wrench marks from where someone wormed it out of the gun without removing the middle band screw, and removing the "vintage" pinch-on sling stud base that likely the same someone beat on tje tube with a claw hammer. So three hours of filing and sanding later I cleaned up the part that shows and trued up the middle band screw notch.
Then I turned and drilled a sleeve for the muzzle band and filed the barrel and magazine tube to accept it, then relieved the band for a snug slip-fit. The sleeve will not only lock the magazine tube in place under recoil but will prevent over-tightening and crushing of the peanut band.
Then I bedded the middle band sleeve to the forearm and barrel so the forearm is locked to the barrel in just one place. The magazine tube does not touch the middle band sleeve or screw, so it is allowed to float everywhere except the muzzle attachment point. Maintaining single, positive contact points should prevent POI shift as the barrel heats. I will bed just the rear face of the forearm and end of the magazine tube to the receiver with RTV silicone to eliminate the few thousandths of wiggle. When I mounted the magazine tube I made sure it had about .005" clearance to the receiver face so it wouldn't bind as the barrel heated.
Now, when it's all back together, it looks original (except for the sling stud on the middle band and having the more modern forearm shape with checkering).
I have a lot of metal polishing and rebluing to do now. Oh, and I checked the receiver tang against two other rifles and it is indeed bent upward a little, so I have to figure out how to fix that without breaking it before I can final fit and bed the buttstock.