The stock, OEM drives (metals) are suppose to be steel in '98, same as up to '04. Considering the age & time and if you're planning to get back into the groove of things riding heavily or more often, being that the plates (fibers & metals) are original, I would replace the fibers & springs as long as the metals are steel & within spec/not warped.
Everybody will have differing opinions based on their discipline of racing (I having competed off-road, mostly enduros, at 70+ miles at a time, for 15+ years in A-Open/250/Vet and my husband has been competing in the same discipline for 30+ years in A-Senior/250/Open), but for what we do and the mileage accumulated, beyond dumping the tranny oil after every race & almost every ride, we prefer steels and a fresh clutch at the start of every season (fibers, springs, pressure plate). I need my clutch to survive a 70+ mile day in the saddle with a lot of slipping, hence why we never liked aluminum plates. MX & Flat-trackers, may have a different view upon what works best in their applications, we need sheer durability based upon the hot, slow going technical stuff encountered and out right mileage we accumulate during each event or ride.