I probably could've found replacements for the stock wiper spindles, but that way lies madness. This way lies shiny stainless steel and bronze.
The new spindles are mostly stainless, but the shaft passes through a bronze bolt. There's enough material there to let me weld in a spreader plate on the inside, to strengthen everything up, at some point.
If I'm really lucky, I've got my calculations right for the sweep of the wipers! Time will tell.
As for wipers, I'm using Land Rover arms, which have a little adapter that fits onto the 6mm shaft to give it a standard wiper-arm spline, and some 13inch (if I'm remembering right) blades.
...if only I could find the set I bought, which are hiding in the shed somewhere. Ah no matter, they'll turn up when I buy replacements.