A 1987 on a G30 frame would have used R-12 (Freon-12) refrigerant. That has been banned in North America since 1996 and world wide since 2010. If a retrofit has not been done, it requires a system flush and a new filter/dryer or accumulator, and may also involve the installation of new seals and/or hoses made of materials compatible with the refrigerant being installed. If a retrofit was done, it probably used R-134a -- which is also being phased out. It can be purchased but there are many places that have purchase restrictions.
There is probably more than a 'recharge' going to be needed.
That year also most likely had a 16.5" tire standard. That size can be found but probably will have to be special ordered.