It is possible and relatively easy, but not sure it is worth the expense. You will need the fairing, headlight unit, mounting bracket, left & right infills, the side fairing brackets and if possible a fox eye headlight loom to modify to fit the older loom. The foxeye model uses 2 relays to control the headlights, a make/break relay controlled by the right handle bar switch and and a change over relay powered from the contacts of the make/break relay and controlled by dimmer switch on the left bar.
Just be aware also that there is an uprated alternator and different rectifier/regulator on the foxeye models to cater for the higher output of the alternator. See difference below.
The 1998 /1999 Squareye
charging output is 12 volts 18 Amps at 5000 rpm
The 2000/2001 Squareye charging output is 14 volts 18 Amps at 5000 rpm
The foxeye 2002/2003 charging output is 14 volts 21 Amps at 5000 rpm
Might even be cheaper to sell your own and buy a foxeye model