Actually, I had to remake the shell before I could put it all together. I noticed that one of my binders wasn`t brazed completely- it even shows up in the pictures posted above
I don`t have end mills or hole saws suitable for mitering these sizes, so I just filed them. Used the Tim Paterek`s ST to BB jigging method to tack the shell to the extension- set shell in the miter and weight with a little piece of scrap rod.
For the lower joint, I clamped the shell to a flat piece of plate with a washer, worked out shims to keep the quill post on center and clamped that all up. With the joint off the edge of the steel plate, it leaves plenty of torch room for tacking both sides. The extension is 1 X .035, and I didn`t like how it fit up against the 7/8 part. in the future, I`ll go back to using the same diameter for both parts.
Since the longest stem bolt I could find was still way too short, I made a little inverted cup and brazed it in place through a couple of small holes drilled through the post wall. The bolt head ends up a couple inches below the top, but I can still reach it easilly with the long end of a stubby L-shaped allen wrench. I don`t have pics of the final work before painting, but I went back and filled some dimples and hollows with silver before sanding smooth. It does look better now.