Did you talk to any builders that do rack and pinion, or only builder that don't? Many tube-chassis drag cars use rack & pinion, it is a very common and popular kit.

I only know personally one guy that did this for a road Datsun. Everybody said it was very difficult. But he just did it and it was simple, I saw the work. He reports that it works well, much better than the stock setup. He has a Datsun 510. He said he used one off a small Datsun. It may have been a B11, but he didn't remember. He was more interested in doing than in talking.