Shortening the steering shaft will also lower the wheel,might be too close to your legs to get in and out of the truck easily.
Welded steering shafts are no problem if you V the ends to get good weld penetration and .There isn't really much twisting force on the shaft if you think about it you apply what,maybe 25 lbs maxiumum rotating effort nine inches from the shaft on these old trucks? Did you ever steer a vehicle with a Vice Grips when the wheel was removed? The real load is on the steering linkage due to the gearing of the steering box.
I welded the shaft on my 37 many years ago,it ain't broke yet
