You are a life saver, Destroyer. I wasn't trying to deminish your excellent idea, I was just poking at you about drilling the axle with the drill press.
The substrate is clean like new. I have Square 2" OD Galvanized Tubing with stubs that fit inside and get welded in place. Thankfully I will be doing the welding on a heavy duty worktable at a comfortable height (ie no vertical welding because it always looks like a$$ when I am done, I need some serious schooling/practice on uphand vertical, thanks for the tip). If I knew in advance I would be welding vertical I would use the mig next door. Actually I still might use the mig, depends on when the parts arrive. Any drawbacks? You sound like the man to ask.
The more I think about spindle alignment the more I think a straight edge and a micrometer may be the ticket. In any case it will be close enough. Worst case scenario, a little extra tire wear, I can live with that since the tires tend to dry rot before the tread is gone anyway.