Silverbear,
Having seen your builds I would say that you are up front with the leaders when it comes to mechanical smarts.
My thoughts are that we will need an outer tube from the neck, welded to the tube coming out from the crank housing as the original had.
Inside we will have to run a 1 inch header tube that has been threaded like a regular bike tube but goes down to an inch or so above the lower tube. From there through the lower tube and out the other side a piece of 3/4 inch round bar that we can weld the pitman arm to, so we can hook up the steering.
I'd like to have a bearing on the lower end of the steering so it won't bind as we turn the steering but that can be figured out as we go.
I have a feeling that the welder/machinist will become our new best friend. May have to help him build a bike. At least he's a close friend of a good welder that can do the work.
Hope this helps.
If it doesn't work we can take it over to BarelyAWake. He'll figure it out because he can make anything.
You otta see his trike. Now that's genius!!! :}
Steve.