Finally I've got around to building the two curves in a separate park to get the spacing completely correct. As you can see, the inner horseshoe collides with the outer one. The reason for this is that the width of Church's tracks, including the catwalks, is narrower than NL2's. Given that I have neither the time nor the skill to make narrower tracks, I have to make a difficult choice: either I change the radius values of the turns, thus gaining the necessary clearance while sacrificing accuracy, or I maintain the radius values and just hope that everyone would rather the track was true to the design than looked pretty, and forgive me in the comments and ratings.
After mulling it over for a while I decided to keep the radius values as they are. My intention since the start has been to get the recreation as close to Church's blueprints as possible. Except for correcting a couple of obvious height errors, every radius, height and banking marking is exactly as written on the blueprint. It would make no sense for me to sacrifice accuracy now, as the first questions people are going to ask will be, "How high, fast and intense was it, and what were the forces?" I want to know as well! So the apparent error will stay for the sake of design accuracy. I've also attached a few photos taken around the turn so you can see how tightly they fit together.