Shouldn't be a problem as you can have more than one perl installed and require the proper one.
On the other hand there are recommendations about those functions and constructs that will be deprecated and usage is not recommended any more, so keep to the advice of those coders and don't use them anymore to enable you to port your code easier. Here it seems to me a good idea to get used to clear procedural and/or OO-programming to help you easily maintain a lot of code with minor changes.

Have a nice day
All decision is left to your taste

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