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Why are you asking? Is it because there is a reason you want or need the gun to not be marked as a .357 Magnum for some legal reason?
Of course, it is well known that there is a complete absence of any illegal firearms in Mexico.
To answer your question, yes, a barrel marked 38 S&W Special can be installed on a Magnum frame. It may require a bit of work but most barrel installs require work.
Considering your laws, you made the correct choice.
Kevin