Following kvales post, I'd like to add that you should write a bunch of tests to ensure that the code you produce works the same way as the original code. It's a hell of its own if you generate a sideeffect you haven't considered before and you'll notice it (too) late.
Agreed. Part of the problem is that the reason for the task is that my employer does not want to spend the $$$ for the fancy analog design workstation software that the process models were created for. A rare instance where lab eggs don't want to spend the peoples' money.