Technically you could convert other coils, however, coils were specifically designed for individual detectors with electrical resistance, impedance, coil balance and connectors in mind. Some coils also have other electronic components in line.
Really if you dont have circuit diagrams for both the detector, coil and the coil you wish to modify then you are really just poking in the dark.
Unless someone has already done the mod and has documented it and it works go for a coil that was made for the detector in question.
This is my own opinion.