I would start with the DICOM definitions.
XC https://www.dicomstandard.org/…ftsup/docs/sups/sup15.pdf
OP https://www.dicomstandard.org/…ftsup/docs/sups/sup91.pdf
OP is a newer and more complex standard and it can contain XC but not the other way around. You might be lucky and there are no extra tags, but it is more likely that you will have to remove many tags to make the files XC compliant.
Mark