Maybe. What is the diameter of the steerer tube on your current bike? If you have a 1-1/8" headset (if th quill of your stem is 25.4mm diameter) then you can probably fit it if you get a new headset and stem.
However, if your bike came with a threaded headset then it is likely almost 20 years old (threaded headsets were almost completely gone from mountain bikes by the mid nineties) then it is likely a ~50mm or less travel fork. A newer fork will push the front end of you bike up an additional 2" which may impact the handling negatively.
Also, if your bike still has the original centre pull cantilever brakes, you will have to switch to v brakes or discs (which would also require a new front wheel) as you cannot mount a canti brake cable stop on the Rockshox fork. You will likely need new brake levers for either of these options, too.
I have to ask - what are you trying to accomplish with this? For a couple hundred dollars more you could get a whole new bike the same quality as what would have come with Suntour forks bak in the 90s. FOr the same price you could likely find something considerably better if you go for a used bike.
IMHO, this would not be as much an 'upgrade' as a 'waste of money.' If you current fork is completely buggered but the rest of the bike is immaculate, then a replacement rigid fork would be a better choice.