The only time I use a rear steer is flipped upside down for my friends down under....takes it from a rear steer LH to front steer RH drive .......works like a charm.
The rear steer rack Unisteer sells is interesting. I saw one at Mopars at the Red Barn in a Challenger. The steering shafts had some serious angles going on......I can only imagine the degree of difficultly in putting one in an A body.
Have you looked into Fat Man Fabrications for the 40s and 50s hot rods?.