Yes it will defintely work. I just did the exact same mod to my car and am very happy with the results. There's a noticable improvement in brake power. All you need is the caliper brackets, all the hardware gets swapped from your 98 bracket onto the WRX bracket. www.northursalia.com
has the whole mod documented.
I opted for a different mod with the rear brakes and went with the turbo legacy vented rear rotors, calipers and caliper brackets. Subaru sells a kit that includes the caliper and bracket all ready to mount up. This is another mod that I'm very pleased with. Its also documented at the web site listed above.
Let me know if you need a set of brackets, I have a pair laying around.