Item code and PO # field length

SOLVED

So I was asked to increase the size of the item code and PO# fields. I know from previous question you can't change the standard out of the box fields you would need to create a UDF.

However, I don't see how you can swap those standard fields for the UDF I would think that "would mess up something up" for a lack of better terms.

Help!!.. Thanks as always ahead of time