Flaming River and others make U-joints to hook up the Cadillac column to the Pinto/MustangII rack. I would get the column where I wanted it.up/down/sideways/in/out and make brackets to hold it. Then secure it at the floor area.....being careful and mindful of the shifting linkage. Them 390's are wide.
You will need at least 2 U-joints IMHO to make it to the rack stub. Maybe 3.
You may need a Support bearing too.....
DO NOT forget to hook up the neutral safety switch