Fib: Here is your info,
I call
THIS the Saginaw option. (CPP 500 series)
I call
THIS the Toyota option. It is supposedly a "CPP design" clone. Actual Toyota boxes become very hard to find. This clone is better and has a better ratio. (CPP 400 series).
The hardest part of DIY is the pitman arm. Next, be sure drag link is level. The rest is straight forward for an engineer. Hook things up and plumb it. Maintain geometry. I've seen many DIY hybrid welded pitman arms. 1/2 fits truck, 1/2 fits donor box. They are forged so the weld will be good.