Back in 2009 there was some traction for conversion to SI units completely.
According to this article,
NASA recently calculated that converting the relevant drawings, software and documentation to the “International System” of units (SI) would cost a total of $370 million – almost half the cost of a 2009 shuttle launch, which costs a total of $759 million. “We found the cost of converting to SI would exceed what we can afford,” says Hautaluoma.
This seems like a very bloated figure. I am sure NASA is literally working on "Rocket Science" and its not going to be easy. How was this figure calculated and how accurate is it?