I believe when Terra found me an old 1/8 barrel she said they had to do something to the new gas block to make it work, or maybe it was to the barrel itself, either way a new gas block on an older barrel is a no-go. I would assume vice-versa would be the same.
You can order the barrel stripped. But, I've got an extra piston head sitting on my bench doing nothing if you want to pay for shipping, it's all yours. PM me.